You searched for subject:(N Polar Gallium Nitride).
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Indian Institute of Science
1.
Yaddanapudi, G R Krishna.
Effect of Process Parameters on the Growth of N-Polar GaN on Sapphire by MOCVD.
Degree: PhD, Faculty of Engineering, 2017, Indian Institute of Science
URL: http://etd.iisc.ac.in/handle/2005/2662 
► Group III-Nitrides (GaN, InN & AlN) are considered one of the most important class of semiconducting materials after Si and GaAs. The excellent optical and…
(more)
▼ Group III-Nitrides (GaN, InN & AlN) are considered one of the most important class of semiconducting materials after Si and GaAs. The excellent optical and electrical properties of these nitrides result in numerous applications in lighting, lasers, and high-power/high-frequency devices. Due to the lack of cheap bulk III-
Nitride substrates, GaN based devices have been developed on foreign substrates like Si, sapphire and SiC. These technologies have been predominantly developed on the so called Ga-polarity epitaxial stacks with growth in the [0001] direction of GaN. It is this orientation that grows most easily on sapphire by metal organic chemical vapor deposition (MOCVD), the most common combination of substrate and deposition method used thus far. The opposite [000¯1] or
N-
polar orientation, very different in properties due to the lack of an inversion centre, offers several ad- vantages that could be exploited for better electronic and optoelectronic devices. However, its growth is more challenging and needs better understanding.
The aim of the work reported in this dissertation was a systematic investigation of the relation between the various growth parameters which control polarity, surface roughness and mosaicity of GaN on non-miscut sapphire (0001) wafers for power electronics and lighting applications, with emphasis on the realization of
N-
polar epitaxial layers. GaN is grown on sapphire (0001) in a two-step process, which involves the deposition of a thin low temperature GaN nucleation layer (NL) on surface modified sapphire followed by the growth of high temperature device quality GaN epitaxial layer. The processing technique used is MOCVD. Various processing methods for synthesis of GaN layers are described with particular em- phasis on MOCVD method. The effect of ex situ cleaning followed by an in situ cleaning on the surface morphology of sapphire (0001) wafers is discussed. The characterization tools used in this dissertation for studying the chemical bond nature of nitrided sapphire surface and microstructural evolution (morphological and structural) of GaN layers are described in detail.
The effect of nitridation temperature (TN) on structural transformation of non- miscut sapphire (0001) surface has been explored. The structural evolution of nitrided layers at different stages of their process like as grown stage and thermal annealing stage is investigated systematically. The chemical bond environment information of the nitrided layers have been examined by x-ray photoelectron spectroscopy (XPS). It is found that high temperature nitridation (TN ≥ 800 °C) results in an Al-
N tetrahedral bond environment on sapphire surface. In contrast, low temperature nitridation (TN = 530 °C) results in a complex Al-O-
N environment on sapphire surfaces. Microstructural evolution of low temperature GaN NLs has been studied at every stage of processing by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface roughness evolution and island size distribution of NLs measured from AFM…
Advisors/Committee Members: Banerjee, Dipankar (advisor), Raghavan, Srinivasan (advisor).
Subjects/Keywords: Semiconductors; Nitrides; Gallium Nitride; N-Polar Gallium Nitride; Metal Organic Chemical Vapor Deposition (MOCVD); Galllium Nitride Growth; High Temperature Gallium Nitride; Low Temperature Gallium Nitride; GaN; Materials Engineering
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APA (6th Edition):
Yaddanapudi, G. R. K. (2017). Effect of Process Parameters on the Growth of N-Polar GaN on Sapphire by MOCVD. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/2662
Chicago Manual of Style (16th Edition):
Yaddanapudi, G R Krishna. “Effect of Process Parameters on the Growth of N-Polar GaN on Sapphire by MOCVD.” 2017. Doctoral Dissertation, Indian Institute of Science. Accessed January 23, 2021.
http://etd.iisc.ac.in/handle/2005/2662.
MLA Handbook (7th Edition):
Yaddanapudi, G R Krishna. “Effect of Process Parameters on the Growth of N-Polar GaN on Sapphire by MOCVD.” 2017. Web. 23 Jan 2021.
Vancouver:
Yaddanapudi GRK. Effect of Process Parameters on the Growth of N-Polar GaN on Sapphire by MOCVD. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2017. [cited 2021 Jan 23].
Available from: http://etd.iisc.ac.in/handle/2005/2662.
Council of Science Editors:
Yaddanapudi GRK. Effect of Process Parameters on the Growth of N-Polar GaN on Sapphire by MOCVD. [Doctoral Dissertation]. Indian Institute of Science; 2017. Available from: http://etd.iisc.ac.in/handle/2005/2662
2.
Lund, Cory Christopher.
Metal-Organic Chemical Vapor Deposition of N-polar InGaN and InN for Electronic Devices.
Degree: 2018, University of California – eScholarship, University of California
URL: http://www.escholarship.org/uc/item/91d3k8dz
► While most commercial gallium nitride (GaN) devices are grown in the (0001) Ga-polar orientation, the N-polar (0001 ̅) orientation is advantageous for heterostructures which can…
(more)
▼ While most commercial gallium nitride (GaN) devices are grown in the (0001) Ga-polar orientation, the N-polar (0001 ̅) orientation is advantageous for heterostructures which can benefit from reversed polarization fields including transistors, photodetectors, solar cells, and optoelectronic devices. One particularly attractive application is tunnel junctions, since GaN/(In,Ga)N/GaN tunnel junction devices rely on the piezoelectric polarization in the N-polar orientation. In these devices the tunneling probability is proportional to the indium composition in the InGaN layer, motivating the investigation of the upper limit of indium incorporation in N-polar InGaN layers embedded into GaN. Devices with high indium mole fraction active regions (>0.25) typically suffer from high defect densities and low quantum efficiency, primarily due to 1) the large 10% lattice mismatch between InN and GaN, and 2) the low thermal stability of InN, requiring significantly lower deposition temperatures compared to GaN layers. The work presented in this thesis addresses the above challenges in multiple ways.First, the deposition of N-polar InGaN layers for tunnel devices will be detailed including the optical, structural, and electrical properties of layers with indium compositions up to 0.46. The electrical performance of N-polar GaN/In0.35Ga0.65N/GaN tunnel diodes will be discussed, including temperature-dependent measurements which confirmed tunneling behavior under reverse bias. Second, the growth of N-polar InN quantum dots and thin films on vicinal GaN base layers will be presented. For thin layers, quantum dot-like features were spontaneously formed to relieve the strain between the InN and GaN layers. For thicker layers above 10 nm, high electron mobilities up to 706 cm2/Vs were measured using Hall effect measurements indicating high quality layers. The properties of GaN/InN/GaN double heterostructures will be presented as well.Next, the use of lattice-engineered InGaN pseudo-substrates (PSs) as base layers for InGaN deposition will be discussed as a strategy to mitigate the lattice mismatch when growing layers with high indium content. Relaxed N-polar InGaN films were grown by MOCVD on N-polar InGaN PSs using a novel digital approach which enabled the deposition of thick layers while maintaining smooth surfaces, and InGaN/GaN multiple quantum wells were deposited on both N-polar and Ga-polar InGaN PSs. The use of the InGaN PSs resulted in InGaN layers with about 50% higher In compositions and enhanced optical properties compared to those grown on traditional GaN templates. Finally, the impurity incorporation behavior of N-polar layers grown at reduced temperatures in the InGaN growth regime will be presented along with the growth and process optimization for the fabrication of reduced temperature p-GaN layers. Although the majority of this thesis focuses on the growth of indium-containing layers, these studies are useful for the fabrication of N-polar devices grown at low temperatures. By minimizing the impurity incorporation and…
Subjects/Keywords: Materials Science; Electrical engineering; Gallium Nitride; InGaN; MOCVD; N-polar
…DenBaars, U.K. Mishra, and S. Keller, “Metal-organic chemical vapor deposition of N-polar
InN… …Digital growth of thick N-polar InGaN films on relaxed InGaN pseudo-substrates,” Appl.
Phys… …organic chemical vapor
deposition of high quality, high indium composition N-polar InGaN layers… …DenBaars, U.K. Mishra, and S. Keller, “Growth of high purity
N-polar (In,Ga)N films,” J… …DenBaars, S. Nakamura, U.K. Mishra, M.J. Kim, and
S. Keller, “Indium segregation in N-polar InGaN…
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APA (6th Edition):
Lund, C. C. (2018). Metal-Organic Chemical Vapor Deposition of N-polar InGaN and InN for Electronic Devices. (Thesis). University of California – eScholarship, University of California. Retrieved from http://www.escholarship.org/uc/item/91d3k8dz
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lund, Cory Christopher. “Metal-Organic Chemical Vapor Deposition of N-polar InGaN and InN for Electronic Devices.” 2018. Thesis, University of California – eScholarship, University of California. Accessed January 23, 2021.
http://www.escholarship.org/uc/item/91d3k8dz.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lund, Cory Christopher. “Metal-Organic Chemical Vapor Deposition of N-polar InGaN and InN for Electronic Devices.” 2018. Web. 23 Jan 2021.
Vancouver:
Lund CC. Metal-Organic Chemical Vapor Deposition of N-polar InGaN and InN for Electronic Devices. [Internet] [Thesis]. University of California – eScholarship, University of California; 2018. [cited 2021 Jan 23].
Available from: http://www.escholarship.org/uc/item/91d3k8dz.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lund CC. Metal-Organic Chemical Vapor Deposition of N-polar InGaN and InN for Electronic Devices. [Thesis]. University of California – eScholarship, University of California; 2018. Available from: http://www.escholarship.org/uc/item/91d3k8dz
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Texas State University – San Marcos
3.
Siddique, Md Anwar.
Diamond on GaN: Hetero Interface and Thermal Transport Study.
Degree: PhD, Materials Science, Engineering, and Commercialization, 2019, Texas State University – San Marcos
URL: https://digital.library.txstate.edu/handle/10877/8459
► III-Nitride based high electron mobility transistors (HEMT) have been in the forefront of the 5G LTE revolution and continue to show promise for next-generation terahertz…
(more)
▼ III-
Nitride based high electron mobility transistors (HEMT) have been in the forefront of the 5G LTE revolution and continue to show promise for next-generation terahertz (THz) communications and radar detection systems. GaN-based HEMT devices possess wide bandwidth and high breakdown voltage due to their high electron velocity, high-density two-dimensional electron gas (2DEG), and large breakdown field. More recently, AlGaN/GaN-based transistors for terahertz (THz) emitters and detectors have been reported that can operate from 0.75 THz to 2.1 THz. Furthermore, AlGaN/GaN HEMTs grown on silicon are reported to have switching speeds as high as ∼150 GHz, while the power densities can exceed 12 W/mm, as well as under harsh operational conditions. The maximum radio frequency (RF) power densities for GaN-based HEMTs reported to date is 41.4 Wmm-1 at 4 GHz. However, the currently fielded and commercially available HEMTs are operating at only 5-6 Wmm-1. This massive gap in performance is due to power loss because of self-heating in the HEMT device, which degrades the power added efficiency (PAE) and eventually causes device failure. This self-heating effect is quite severe and can cause a temperature rise in the device as high as 350 ˚C while operating at 7.8 Wmm-1. Creating a low thermally resistive pathway using chemical vapor deposition (CVD) diamond at very close proximity to the self-heating source could effectively dissipate heat, thereby mitigating the self-heating problem. The challenge here is to find the thinnest possible dielectric adhesion layer with low thermal boundary resistance (TBR) to facilitate diamond growth on the HEMT and to protect it from the harsh CVD diamond growth environment. We have developed and optimized in-situ SiNx using metal organic chemical vapor deposition (MOCVD) for use as a dielectric adhesion layer to facilitate diamond growth. We report on the effect of reactant gas stoichiometry of in-situ SiNx passivation on structural and electrical properties of MOCVD grown AlGaN/GaN HEMT structures on 100 mm Si (111). A systematic study on the effect of constituent gas flows on surface morphology and growth rate is reported. X-ray reflectometry and atomic force microscopy is performed to determine the surface morphology and thickness of the near-surface layers. Conformal coverage of SiNx with abrupt SiNx -III-
Nitride interface is confirmed by transmission electron microscopy. When the growth rate of the in-situ SiNx is less than a critical threshold of 10 nm/hr, the AlGaN barrier layer is significantly etched. The charge density of the 2DEG induced at the AlGaN/GaN interface due to polarization and surface state filling is evaluated with Hg-probe C-V profile and calculations based on strain relaxation. Sheet charge density, electron mobility, and sheet resistance were determined by measuring Cloverleaf Hall structures. Passivated samples with growth rates higher than the critical threshold show excellent suppression of strain relaxation in the barrier layer. In addition to the strain induced…
Advisors/Committee Members: Piner, Edwin L. (advisor), Holtz, Mark W. (committee member), Droopad, Ravi (committee member), Smith, Casey E. (committee member), Harris, Harlan R. (committee member).
Subjects/Keywords: GaN; Diamond; HRXRD; III-N; in-situ SiNx; Gallium nitride; Semiconductors – Materials; Transistors
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APA (6th Edition):
Siddique, M. A. (2019). Diamond on GaN: Hetero Interface and Thermal Transport Study. (Doctoral Dissertation). Texas State University – San Marcos. Retrieved from https://digital.library.txstate.edu/handle/10877/8459
Chicago Manual of Style (16th Edition):
Siddique, Md Anwar. “Diamond on GaN: Hetero Interface and Thermal Transport Study.” 2019. Doctoral Dissertation, Texas State University – San Marcos. Accessed January 23, 2021.
https://digital.library.txstate.edu/handle/10877/8459.
MLA Handbook (7th Edition):
Siddique, Md Anwar. “Diamond on GaN: Hetero Interface and Thermal Transport Study.” 2019. Web. 23 Jan 2021.
Vancouver:
Siddique MA. Diamond on GaN: Hetero Interface and Thermal Transport Study. [Internet] [Doctoral dissertation]. Texas State University – San Marcos; 2019. [cited 2021 Jan 23].
Available from: https://digital.library.txstate.edu/handle/10877/8459.
Council of Science Editors:
Siddique MA. Diamond on GaN: Hetero Interface and Thermal Transport Study. [Doctoral Dissertation]. Texas State University – San Marcos; 2019. Available from: https://digital.library.txstate.edu/handle/10877/8459
4.
Rennesson, Stéphanie.
Développement de nouvelles hétérostructures HEMTs à base de nitrure de gallium pour des applications de puissance en gamme d'ondes millimétriques : Development of new gallium nitride based HEMT heterostructures for microwave power applications.
Degree: Docteur es, Physique, 2013, Nice
URL: http://www.theses.fr/2013NICE4106
► Les matériaux III-N sont présents dans la vie quotidienne pour des applications optoélectroniques (diodes électroluminescentes, lasers). Les propriétés remarquables du GaN (grand gap, grand champ…
(more)
▼ Les matériaux III-N sont présents dans la vie quotidienne pour des applications optoélectroniques (diodes électroluminescentes, lasers). Les propriétés remarquables du GaN (grand gap, grand champ de claquage, champ de polarisation élevé, vitesse de saturation des électrons importante…) en font un candidat de choix pour des applications en électronique de puissance à basse fréquence, mais aussi à haute fréquence, par exemple en gamme d'ondes millimétriques. L’enjeu de ce travail de thèse consiste à augmenter la fréquence de travail des transistors tout en maintenant une puissance élevée. Pour cela, des hétérostructures HEMTs (High Electron Mobility Transistors) sont développées et les épaisseurs de cap et de barrière doivent être réduites, bien que ceci soit au détriment de la puissance délivrée. Une étude sera donc menée sur l’influence des épaisseurs de cap et de barrière ainsi que le type de barrière (AlGaN, AlN et InAlN) de manière à isoler les hétérostructures offrant le meilleur compromis en termes de fréquence et de puissance. De plus, les moyens mis en œuvre pour augmenter la fréquence de travail entrainent une dégradation du confinement des électrons du canal. De manière à limiter cet effet, une back-barrière est insérée sous le canal. Ceci fera l’objet d’une deuxième étude. Enfin, une étude de la passivation de surface des transistors sera menée. La combinaison des ces trois études permettra d’identifier la structure optimale pour délivrer le plus de puissance à haute fréquence (ici à 40 GHz).
Nitride based materials are present in everyday life for optoelectronic applications (light emitting diodes, lasers). GaN remarkable properties (like large energy band gap, high breakdown electric field, high polarization field, high electronic saturation velocity…) make it a promising candidate for low frequency power electronic applications, but also for high frequency like microwaves range for example. The aim of this work is to increase the transistors working frequency by keeping a high power. To do this, high electron mobility transistor heterostructures are developed, and cap and barrier thicknesses have to be reduced, although it is detrimental for a high power. A first study deals with the influence of cap and barrier thicknesses as well as the type of barrier (AlGaN, AlN and InAlN), in order to isolate heterostructures offering the best compromise in terms of power and frequency. Moreover, the means implemented to increase the working frequency lead to electron channel confinement degradation. In order limit this effect, a back-barrier is added underneath the channel. It will be the subject of the second study. Finally, a transistor surface passivation study will be led. The combination of those three parts will allow identifying the optimum structure to deliver the highest power at high frequency (here at 40 GHz).
Advisors/Committee Members: Cordier, Yvon (thesis director).
Subjects/Keywords: Transistor à haute mobilité électronique; Nitrure de gallium; III-N; Épitaxie; Transistor de puissance; RF; Ondes millimétriques; High electron mobility transistor; Gallium nitride; III-N; Epitaxy; Power transistor; RF; Microwaves
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APA ·
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APA (6th Edition):
Rennesson, S. (2013). Développement de nouvelles hétérostructures HEMTs à base de nitrure de gallium pour des applications de puissance en gamme d'ondes millimétriques : Development of new gallium nitride based HEMT heterostructures for microwave power applications. (Doctoral Dissertation). Nice. Retrieved from http://www.theses.fr/2013NICE4106
Chicago Manual of Style (16th Edition):
Rennesson, Stéphanie. “Développement de nouvelles hétérostructures HEMTs à base de nitrure de gallium pour des applications de puissance en gamme d'ondes millimétriques : Development of new gallium nitride based HEMT heterostructures for microwave power applications.” 2013. Doctoral Dissertation, Nice. Accessed January 23, 2021.
http://www.theses.fr/2013NICE4106.
MLA Handbook (7th Edition):
Rennesson, Stéphanie. “Développement de nouvelles hétérostructures HEMTs à base de nitrure de gallium pour des applications de puissance en gamme d'ondes millimétriques : Development of new gallium nitride based HEMT heterostructures for microwave power applications.” 2013. Web. 23 Jan 2021.
Vancouver:
Rennesson S. Développement de nouvelles hétérostructures HEMTs à base de nitrure de gallium pour des applications de puissance en gamme d'ondes millimétriques : Development of new gallium nitride based HEMT heterostructures for microwave power applications. [Internet] [Doctoral dissertation]. Nice; 2013. [cited 2021 Jan 23].
Available from: http://www.theses.fr/2013NICE4106.
Council of Science Editors:
Rennesson S. Développement de nouvelles hétérostructures HEMTs à base de nitrure de gallium pour des applications de puissance en gamme d'ondes millimétriques : Development of new gallium nitride based HEMT heterostructures for microwave power applications. [Doctoral Dissertation]. Nice; 2013. Available from: http://www.theses.fr/2013NICE4106
5.
Hautakangas, Sami.
Impurity Decoration of Native Vacancies in Ga and N Sublattices of Gallium Nitride.
Degree: 2005, Helsinki University of Technology
URL: http://lib.tkk.fi/Diss/2005/isbn9512276674/
► The effects of impurity atoms as well as various growth methods to the formation of vacancy type defects in gallium nitride (GaN) have been studied…
(more)
▼ The effects of impurity atoms as well as various growth methods to the formation of vacancy type defects in gallium nitride (GaN) have been studied by positron annihilation spectroscopy. It is shown that vacancy defects are formed in Ga or N sublattices depending on the doping of the material. Vacancies are decorated with impurity atoms leading to the compensation of the free carriers of the samples. In addition, the vacancy clusters are found to be present in significant concentrations in n-type as well as in p-type GaN. Nitrogen vacancies compensate Mg impurities in magnesium doped GaN. The high Mg content creates a defect profile with a low vacancy concentration near the surface. Post-growth annealing dissociates Vn-related complexes activating the p-type conductivity. Also the vacancy profile is made homogeneous by thermal treatment in highly Mg-doped GaN. The direct experimental evidence of oxygen decorated Ga vacancy is obtained in O-doped n-type GaN. The present study shows that VGa-ON is distinguishable from an isolated Ga vacancy by positron annihilation spectroscopy. Yellow luminescence (YL) is common in n-type GaN, which is usually related to Ga vacancy defects. However, carbon doped semi-insulating GaN is exhibiting strong YL emission, but without the presence of Ga vacancies. The YL is attributed to C interstitials. The investigations concerning silicon doped GaN and GaN grown by the mass-transport method reveal vacancy type defects, which were identified as vacancy clusters.
Dissertations of Laboratory of Physics, Helsinki University of Technology, ISSN 1455-1802; 132
Advisors/Committee Members: Helsinki University of Technology, Department of Engineering Physics and Mathematics, Laboratory of Physics.
Subjects/Keywords: gallium nitride; positron annihilation; vacancy
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APA ·
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APA (6th Edition):
Hautakangas, S. (2005). Impurity Decoration of Native Vacancies in Ga and N Sublattices of Gallium Nitride. (Thesis). Helsinki University of Technology. Retrieved from http://lib.tkk.fi/Diss/2005/isbn9512276674/
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Hautakangas, Sami. “Impurity Decoration of Native Vacancies in Ga and N Sublattices of Gallium Nitride.” 2005. Thesis, Helsinki University of Technology. Accessed January 23, 2021.
http://lib.tkk.fi/Diss/2005/isbn9512276674/.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hautakangas, Sami. “Impurity Decoration of Native Vacancies in Ga and N Sublattices of Gallium Nitride.” 2005. Web. 23 Jan 2021.
Vancouver:
Hautakangas S. Impurity Decoration of Native Vacancies in Ga and N Sublattices of Gallium Nitride. [Internet] [Thesis]. Helsinki University of Technology; 2005. [cited 2021 Jan 23].
Available from: http://lib.tkk.fi/Diss/2005/isbn9512276674/.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hautakangas S. Impurity Decoration of Native Vacancies in Ga and N Sublattices of Gallium Nitride. [Thesis]. Helsinki University of Technology; 2005. Available from: http://lib.tkk.fi/Diss/2005/isbn9512276674/
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Cornell University
6.
Brown, Richard.
Advanced Dielectrics For Gallium Nitride Power Electronics.
Degree: PhD, Electrical Engineering, 2011, Cornell University
URL: http://hdl.handle.net/1813/33475
► This dissertation details the synthesis, characterization, and application of low-pressure chemical vapor deposited (LPCVD) Aluminum Silicon Nitride (Al x Siy Nz ) dielectrics to AlGaN/GaN…
(more)
▼ This dissertation details the synthesis, characterization, and application of low-pressure chemical vapor deposited (LPCVD) Aluminum Silicon
Nitride (Al x Siy Nz ) dielectrics to AlGaN/GaN based high electron mobility transistors (HEMTs). A detailed study of the effect on A fabrication process for such devices utilizing the Al x Siy Nz passivation is presented, and their performance at frequencies ranging from DC to the microwave is compared to devices utilizing more traditional Siy Nz films for the same purpose. As AlGaN/GaN HEMT technology has matured, much focus has been placed on the passivation dielectric itself, as many parasitic device mechanisms are directly influenced by it. Metrics such as breakdown voltage, efficiency, and high-frequency dispersion are all greatly affected by the type of passivation applied. In this work the application of LPCVD Al x Siy Nz films as AlGaN/GaN HEMT passivants is presented and shown to yield superior devices to ones passivated with similarly deposited Siy Nz dielectrics. Breakdown voltage, power added efficiency (PAE), output power density were all measured to be superior on the Al x Siy Nz passivated devices when measured under large-signal conditions at 10 GHz.
Advisors/Committee Members: Shealy, James Richard (chair), Eastman, Lester Fuess (committee member), Blakely, John M (committee member).
Subjects/Keywords: Gallium Nitride; hemt; Dielectric
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APA (6th Edition):
Brown, R. (2011). Advanced Dielectrics For Gallium Nitride Power Electronics. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/33475
Chicago Manual of Style (16th Edition):
Brown, Richard. “Advanced Dielectrics For Gallium Nitride Power Electronics.” 2011. Doctoral Dissertation, Cornell University. Accessed January 23, 2021.
http://hdl.handle.net/1813/33475.
MLA Handbook (7th Edition):
Brown, Richard. “Advanced Dielectrics For Gallium Nitride Power Electronics.” 2011. Web. 23 Jan 2021.
Vancouver:
Brown R. Advanced Dielectrics For Gallium Nitride Power Electronics. [Internet] [Doctoral dissertation]. Cornell University; 2011. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/1813/33475.
Council of Science Editors:
Brown R. Advanced Dielectrics For Gallium Nitride Power Electronics. [Doctoral Dissertation]. Cornell University; 2011. Available from: http://hdl.handle.net/1813/33475
7.
Malkowski, Thomas.
High-Temperature Growth of Gallium Nitride Using the Ammonothermal Method with Ammonium Chloride Mineralizer.
Degree: 2016, University of California – eScholarship, University of California
URL: http://www.escholarship.org/uc/item/1tf7z2bm
► Gallium nitride (GaN) has become an important semiconductor for the optoelectronics and power electronics fields in the pursuit of high efficiency devices. However, the lack…
(more)
▼ Gallium nitride (GaN) has become an important semiconductor for the optoelectronics and power electronics fields in the pursuit of high efficiency devices. However, the lack of a natural native GaN substrate has forced growth of GaN devices on foreign substrates such as sapphire, silicon carbide, and silicon. To further enhance efficiency and develop devices with longer lifetimes, the number of defects present in devices must be reduced. The development of a native GaN substrate of high crystalline quality would directly enable defect reduction. The ammonothermal method of GaN growth has shown significant promise as a technique for the production of high quality GaN crystals of industrially significant size (crystals on the order of centimeters in the largest dimension). The ammonothermal method is a solvothermal method that uses a mineralizer (here ammonium chloride) with supercritical ammonia to transport GaN from a source material from one temperature zone to grow a seed crystal in another temperature zone. High pressures, high temperatures, and the presence of a highly corrosive chemistry make development of an economical growth reactor challenging. This body of work outlines the development of a growth reactor capable of high temperature ammonothermal growth of GaN using ammonium chloride mineralizer.Initial development of the ammonothermal reactor required identification of suitable reactor materials. A materials stability study was conducted by exposing samples of materials to the ammonothermal environment and measuring mass loss as well as any chemical or mechanical changes that occurred. An Inconel 625 alloy reactor was employed, although the reactor itself was somewhat susceptible to corrosion from the ammonothermal environment. The study yielded a subset of materials that may be suitable for use as gaskets and other single use items which include niobium, molybdenum, titanium, vanadium, tungsten, gold, and platinum. Alloys of molybdenum and cobalt may also be useful. High strength titanium-zirconium-molybdenum (TZM) was also identified as a corrosion resistant material and was selected for reactor design.A TZM reactor was then designed and fabricated. Subsequent high pressure, high temperature tests indicated that TZM was essentially inert and growth of GaN crystals followed. All GaN growth was accomplished at or above 650°C using seed crystals grown by hydride vapor phase epitaxy. Seeds were characterized by micrometer measurements for growth thickness, x-ray diffraction (XRD) for crystalline quality, and secondary ion mass spectrometry (SIMS) for impurity concentrations. The growth quality appeared to match the seed quality as measured by XRD. Growth coloration ranged from slightly gray to green or yellow with growth rates up to 191 µm/day. Most seeds exhibited significant faceting at the edges of the sample, forming semipolar planes. SIMS was performed on a couple of samples which indicated oxygen concentrations of ~1018 cm¬-3.
Subjects/Keywords: Materials Science; ammonothermal; gallium nitride
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APA (6th Edition):
Malkowski, T. (2016). High-Temperature Growth of Gallium Nitride Using the Ammonothermal Method with Ammonium Chloride Mineralizer. (Thesis). University of California – eScholarship, University of California. Retrieved from http://www.escholarship.org/uc/item/1tf7z2bm
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Malkowski, Thomas. “High-Temperature Growth of Gallium Nitride Using the Ammonothermal Method with Ammonium Chloride Mineralizer.” 2016. Thesis, University of California – eScholarship, University of California. Accessed January 23, 2021.
http://www.escholarship.org/uc/item/1tf7z2bm.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Malkowski, Thomas. “High-Temperature Growth of Gallium Nitride Using the Ammonothermal Method with Ammonium Chloride Mineralizer.” 2016. Web. 23 Jan 2021.
Vancouver:
Malkowski T. High-Temperature Growth of Gallium Nitride Using the Ammonothermal Method with Ammonium Chloride Mineralizer. [Internet] [Thesis]. University of California – eScholarship, University of California; 2016. [cited 2021 Jan 23].
Available from: http://www.escholarship.org/uc/item/1tf7z2bm.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Malkowski T. High-Temperature Growth of Gallium Nitride Using the Ammonothermal Method with Ammonium Chloride Mineralizer. [Thesis]. University of California – eScholarship, University of California; 2016. Available from: http://www.escholarship.org/uc/item/1tf7z2bm
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Chicago
8.
Sarkar, Ketaki.
Study of Wide-Band Gap Oxide and Nitride-Based Semiconductors: Characterization and Device Physics.
Degree: 2018, University of Illinois – Chicago
URL: http://hdl.handle.net/10027/22600
► The increasing need for short wavelength material alongside high-power and high-frequency devices have encouraged a strong wave of research amongst the scientific community. While the…
(more)
▼ The increasing need for short wavelength material alongside high-power and high-frequency devices have encouraged a strong wave of research amongst the scientific community. While the breakthroughs in the high-quality growth of these materials have been achieved demonstrating promising device applications, further research is warranted in terms of control of electronics structure, improvement in crystalline quality, better control over defects and impurities, more efficient device designs etc. This dissertation work aims at characterizing & understanding the dynamics and the underlying physics of wide band gap oxide and
nitride-based semiconductors to push further the potential applications of these materials based devices.
In the first part of the study, a simple and efficient Ar-plasma treatment is proposed to passivate surface traps or defects to significantly improve the near-band-edge (NBE) emission from ZnO nanostructures. Furthermore, improved carrier dynamics with faster relaxation time due to surface treatments from these oxide nanostructures have been studied and analyzed in detail. Effect of morphology, as well as surface treatment on the lasing properties from these structures, have been presented alongside. Another synergistic study of ZnO co-existing with In2O3 nanostructures have been reported which encompasses several elemental and optical characterization techniques to analyze this ensemble of nanostructures.
In the second part of the work, Raman analysis of a very short period AlN/GaN-based superlattice structure has been studied in detail to understand the vibrational properties. Furthermore, the behavior the superlattice under the impact of high-excitation and high-temperature, both of which are the operating condition of high power device has been addressed.
Advisors/Committee Members: Dutta, Mitra (advisor), Stroscio, Michael A (committee member), Shi, Junxia (Lucy) (committee member), Metlushko, Vitali (committee member), Nicholls, Alan (committee member), Dutta, Mitra (chair).
Subjects/Keywords: Zinc Oxide; Gallium Nitride
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APA (6th Edition):
Sarkar, K. (2018). Study of Wide-Band Gap Oxide and Nitride-Based Semiconductors: Characterization and Device Physics. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22600
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Sarkar, Ketaki. “Study of Wide-Band Gap Oxide and Nitride-Based Semiconductors: Characterization and Device Physics.” 2018. Thesis, University of Illinois – Chicago. Accessed January 23, 2021.
http://hdl.handle.net/10027/22600.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Sarkar, Ketaki. “Study of Wide-Band Gap Oxide and Nitride-Based Semiconductors: Characterization and Device Physics.” 2018. Web. 23 Jan 2021.
Vancouver:
Sarkar K. Study of Wide-Band Gap Oxide and Nitride-Based Semiconductors: Characterization and Device Physics. [Internet] [Thesis]. University of Illinois – Chicago; 2018. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/10027/22600.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Sarkar K. Study of Wide-Band Gap Oxide and Nitride-Based Semiconductors: Characterization and Device Physics. [Thesis]. University of Illinois – Chicago; 2018. Available from: http://hdl.handle.net/10027/22600
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Maryland
9.
Khan, Muhammad Raziuddin A.
Design and Characterization of p-i-n Devices for Betavoltaic Microbatteries on Gallium Nitride.
Degree: Electrical Engineering, 2015, University of Maryland
URL: http://hdl.handle.net/1903/17220
► Betavoltaic microbatteries convert nuclear energy released as beta particles directly into electrical energy. These batteries are well suited for electrical applications such as micro-electro-mechanical systems…
(more)
▼ Betavoltaic microbatteries convert nuclear energy released as beta particles directly into electrical energy. These batteries are well suited for electrical applications such as micro-electro-mechanical systems (MEMS), implantable medical devices and sensors. Such devices are often located in hard to access places where long life, micro-size and lightweight are required. The working principle of a betavoltaic device is similar to a photovoltaic device; they differ only in that the electron hole pairs (EHPs) are generated in the device by electrons instead of photons.
In this study, the performance of a betavoltaic device fabricated from
gallium nitride (GaN) is investigated for beta particle energies equivalent to Tritium (3H) and Nickel-63 (N63) beta sources. GaN is an attractive choice for fabricating betavoltaic devices due to its wide band gap and radiation resistance. Another advantage GaN has is that it can be alloyed with aluminum (Al) to further increase the bandgap, resulting in a higher output power and increased efficiency.
Betavoltaic devices were fabricated on p-i-
n GaN structures grown by metalorganic chemical vapor deposition (MOCVD). The devices were characterized using current - voltage (IV) measurements without illumination (light or beta), using a laser driven light source, and under an electron beam. Dark IV measurements showed a turn on-voltage of ~ 3.4 V, specific-on-resistance of 15.1 m Ω-cm2, and a leakage current of 0.5 mA at – 10 V. A clear photo-response was observed when IV curves were measured for these devices under a light source at a wavelength of 310 nm (4.0 eV). These devices were tested under an electron beam in order to evaluate their behavior as betavoltaic microbatteries without using radioactive materials. Output power of 70 nW and 640 nW with overall efficiencies of 1.2% and 4.0% were determined at the average energy emission of 3H (5.6 keV) and 63N (17 keV) respectively.
Advisors/Committee Members: Iliadis, Agis A. (advisor).
Subjects/Keywords: Electrical engineering; Energy; Betavoltaic Microbatteries; electron-beam; Gallium Nitride; Nickel-63; p-i-n diode; Tritium
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APA ·
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APA (6th Edition):
Khan, M. R. A. (2015). Design and Characterization of p-i-n Devices for Betavoltaic Microbatteries on Gallium Nitride. (Thesis). University of Maryland. Retrieved from http://hdl.handle.net/1903/17220
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Khan, Muhammad Raziuddin A. “Design and Characterization of p-i-n Devices for Betavoltaic Microbatteries on Gallium Nitride.” 2015. Thesis, University of Maryland. Accessed January 23, 2021.
http://hdl.handle.net/1903/17220.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Khan, Muhammad Raziuddin A. “Design and Characterization of p-i-n Devices for Betavoltaic Microbatteries on Gallium Nitride.” 2015. Web. 23 Jan 2021.
Vancouver:
Khan MRA. Design and Characterization of p-i-n Devices for Betavoltaic Microbatteries on Gallium Nitride. [Internet] [Thesis]. University of Maryland; 2015. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/1903/17220.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Khan MRA. Design and Characterization of p-i-n Devices for Betavoltaic Microbatteries on Gallium Nitride. [Thesis]. University of Maryland; 2015. Available from: http://hdl.handle.net/1903/17220
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Anna University
10.
Puviarasu P.
Studies on the growth and characterisation of gallium
nitride using chloride vapour phase epitaxy and the effect of swift
heavy ion irradiations on gallium nitride epilayers;.
Degree: Studies on the growth and characterisation of gallium
nitride using chloride vapour phase epitaxy and the effect of swift
heavy ion irradiations on gallium nitride epilayers, 2014, Anna University
URL: http://shodhganga.inflibnet.ac.in/handle/10603/24564
► Group III nitrides such as Indium Nitride Gallium Nitride and Aluminium Nitride are currently the most challenging and technologically important materials which have the potential…
(more)
▼ Group III nitrides such as Indium Nitride Gallium
Nitride and Aluminium Nitride are currently the most challenging
and technologically important materials which have the potential
for optical devices for the entire visible spectrum and extending
far into the ultraviolet wavelengths The best understood III
nitride semiconductor is GaN with a bandgap of 340 eV at room
temperature In addition GaN is the most favorable material system
for high power electronic devices that can operate at high
temperatures GaN substrate material is not widely available for
homoepitaxial growth due to the difficulties in GaN bulk crystal
growth Hence GaN layers are grown heteroepitaxially on foreign
substrates such as sapphire and silicon carbide which introduce
high dislocation density in the grown layer due to large lattice
mismatch and thermal issues GaN epitaxial layers are grown by metal
organic chemical vapour deposition molecular beam epitaxy and
hydride vapour phase epitaxy methods for further processing as
functional devices The process of epitaxy is also unique in its
ability to control the composition and doping Using epitaxy the
electronic and optical properties of a material can be engineered
to create device structures with unique characteristics
newline
Advisors/Committee Members: Kumar J.
Subjects/Keywords: Aluminium nitride; Chloride vapour phase epitaxy; Epitaxial techniques; Gallium nitride; Gallium nitride epilayers; Indium nitride; Science and humanities
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
P, P. (2014). Studies on the growth and characterisation of gallium
nitride using chloride vapour phase epitaxy and the effect of swift
heavy ion irradiations on gallium nitride epilayers;. (Thesis). Anna University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/24564
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
P, Puviarasu. “Studies on the growth and characterisation of gallium
nitride using chloride vapour phase epitaxy and the effect of swift
heavy ion irradiations on gallium nitride epilayers;.” 2014. Thesis, Anna University. Accessed January 23, 2021.
http://shodhganga.inflibnet.ac.in/handle/10603/24564.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
P, Puviarasu. “Studies on the growth and characterisation of gallium
nitride using chloride vapour phase epitaxy and the effect of swift
heavy ion irradiations on gallium nitride epilayers;.” 2014. Web. 23 Jan 2021.
Vancouver:
P P. Studies on the growth and characterisation of gallium
nitride using chloride vapour phase epitaxy and the effect of swift
heavy ion irradiations on gallium nitride epilayers;. [Internet] [Thesis]. Anna University; 2014. [cited 2021 Jan 23].
Available from: http://shodhganga.inflibnet.ac.in/handle/10603/24564.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
P P. Studies on the growth and characterisation of gallium
nitride using chloride vapour phase epitaxy and the effect of swift
heavy ion irradiations on gallium nitride epilayers;. [Thesis]. Anna University; 2014. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/24564
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Anna University
11.
Suresh kumar V.
Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;.
Degree: Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers, 2015, Anna University
URL: http://shodhganga.inflibnet.ac.in/handle/10603/41814
► Gallium nitride GaN is one of the most promising materials newlineamong group III nitrides because its bandgap of 34 eV makes it the best newlinecandidate…
(more)
▼ Gallium nitride GaN is one of the most promising
materials newlineamong group III nitrides because its bandgap of 34
eV makes it the best newlinecandidate for devices operating in the
blue or UV part of the electromagnetic newlinespectrum GaN is
mainly used in light emitting diodes LEDs laser diodes newlineLDs
ultraviolet detectors colour displays and microwave devices GaN is
newlinethe favourable material system for hightemperature and
highpower newlineelectronic devices newlineGaN nanostructures have
attracted much attention because of their newlinepotential for the
near visible and UV optoelectronic applications GaN
newlinenanostructures are mostly grown by vapourliquidsolid method
MBE and newlineHVPE methods newline newline
newline
Reference p. 119-133
Advisors/Committee Members: Kumar J.
Subjects/Keywords: gallium nitride; nanostructures; science and humanities
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
V, S. k. (2015). Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;. (Thesis). Anna University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/41814
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
V, Suresh kumar. “Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;.” 2015. Thesis, Anna University. Accessed January 23, 2021.
http://shodhganga.inflibnet.ac.in/handle/10603/41814.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
V, Suresh kumar. “Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;.” 2015. Web. 23 Jan 2021.
Vancouver:
V Sk. Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;. [Internet] [Thesis]. Anna University; 2015. [cited 2021 Jan 23].
Available from: http://shodhganga.inflibnet.ac.in/handle/10603/41814.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
V Sk. Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;. [Thesis]. Anna University; 2015. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/41814
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Rochester Institute of Technology
12.
Hartensveld, Matthew.
Optimization of Dry and Wet GaN Etching to Form High Aspect Ratio Nanowires.
Degree: MS, School of Chemistry and Materials Science (COS), 2018, Rochester Institute of Technology
URL: https://scholarworks.rit.edu/theses/9835
► Nanowire devices are emerging as the replacement technology to planar devices, such as Light Emitting Diodes (LEDs) and Field Effect Transistors (FETs), due to…
(more)
▼ Nanowire devices are emerging as the replacement technology to planar devices, such as Light Emitting Diodes (LEDs) and Field Effect Transistors (FETs), due to better performance and higher device densities. Here, top-down GaN nanowire fabrication is studied through the use of dry and wet etching techniques. Specifically, dry etching is studied focusing on the effects of etching power, pressure, and the use of chloroform during the process. Wet etching of GaN nanowires takes the initial structures formed by the dry etch to create the desired high aspect ratio, tunable-diameter nanowires. Effects of etching time, temperature, concentration, and ability to remove etch damage are thoroughly studied. Insights of these results are utilized to form high aspect ratio vertical wires with diameters smaller than 100 nm for high performance GaN devices.
Advisors/Committee Members: Jing Zhang.
Subjects/Keywords: Etching; Gallium nitride; GaN; KOH; Nanowire; Nanowires
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APA ·
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APA (6th Edition):
Hartensveld, M. (2018). Optimization of Dry and Wet GaN Etching to Form High Aspect Ratio Nanowires. (Masters Thesis). Rochester Institute of Technology. Retrieved from https://scholarworks.rit.edu/theses/9835
Chicago Manual of Style (16th Edition):
Hartensveld, Matthew. “Optimization of Dry and Wet GaN Etching to Form High Aspect Ratio Nanowires.” 2018. Masters Thesis, Rochester Institute of Technology. Accessed January 23, 2021.
https://scholarworks.rit.edu/theses/9835.
MLA Handbook (7th Edition):
Hartensveld, Matthew. “Optimization of Dry and Wet GaN Etching to Form High Aspect Ratio Nanowires.” 2018. Web. 23 Jan 2021.
Vancouver:
Hartensveld M. Optimization of Dry and Wet GaN Etching to Form High Aspect Ratio Nanowires. [Internet] [Masters thesis]. Rochester Institute of Technology; 2018. [cited 2021 Jan 23].
Available from: https://scholarworks.rit.edu/theses/9835.
Council of Science Editors:
Hartensveld M. Optimization of Dry and Wet GaN Etching to Form High Aspect Ratio Nanowires. [Masters Thesis]. Rochester Institute of Technology; 2018. Available from: https://scholarworks.rit.edu/theses/9835
University of Alberta
13.
von Hauff, Peter A.
Metal Oxide Processing on Gallium Nitride and Silino.
Degree: MS, Department of Electrical and Computer
Engineering, 2012, University of Alberta
URL: https://era.library.ualberta.ca/files/pz50gw42f
► III-V Nitrides are intriguing semiconductors for high-power RF amplifiers and other applications. Gallium Nitride has become popular for mm-HFETs due to its material properties. The…
(more)
▼ III-V Nitrides are intriguing semiconductors for
high-power RF amplifiers and other applications. Gallium Nitride
has become popular for mm-HFETs due to its material properties. The
HFET however, has yet to fully realize the full potential of GaN.
MOSFETs provide an ideal structure because they can provide a true
off-state while increasing the possible breakdown voltage.
Deposition techniques for low defect density oxides must be further
developed to fully realize GaN MOSFET technology. Atomic Layer
Deposition provides a promising process technique by which to
deposit low defect density oxides on GaN. Controlling surface
chemistry can allow deposition of low defect oxides on a wide range
of semiconductors including Silicon.
Subjects/Keywords: Atomic Layer Depostion; metal oxides; Gallium Nitride
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APA ·
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MLA ·
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APA (6th Edition):
von Hauff, P. A. (2012). Metal Oxide Processing on Gallium Nitride and Silino. (Masters Thesis). University of Alberta. Retrieved from https://era.library.ualberta.ca/files/pz50gw42f
Chicago Manual of Style (16th Edition):
von Hauff, Peter A. “Metal Oxide Processing on Gallium Nitride and Silino.” 2012. Masters Thesis, University of Alberta. Accessed January 23, 2021.
https://era.library.ualberta.ca/files/pz50gw42f.
MLA Handbook (7th Edition):
von Hauff, Peter A. “Metal Oxide Processing on Gallium Nitride and Silino.” 2012. Web. 23 Jan 2021.
Vancouver:
von Hauff PA. Metal Oxide Processing on Gallium Nitride and Silino. [Internet] [Masters thesis]. University of Alberta; 2012. [cited 2021 Jan 23].
Available from: https://era.library.ualberta.ca/files/pz50gw42f.
Council of Science Editors:
von Hauff PA. Metal Oxide Processing on Gallium Nitride and Silino. [Masters Thesis]. University of Alberta; 2012. Available from: https://era.library.ualberta.ca/files/pz50gw42f
Anna University
14.
Munawar Basha S.
Investigations on the magnetic properties of doped
gallium nitride ion irradiation studies and nanostructure
growth;.
Degree: 2014, Anna University
URL: http://shodhganga.inflibnet.ac.in/handle/10603/14542
► Gallium nitride (GaN) is by far more extensively studied than the newlineother III-nitrides because of its technological status. It has a wide direct band newlinegap…
(more)
▼ Gallium nitride (GaN) is by far more extensively
studied than the newlineother III-nitrides because of its
technological status. It has a wide direct band newlinegap of 3.4
eV, thus making it suitable candidate for devices operating in blue
newlineto ultra violet region of the electromagnetic spectrum. It
is mainly used in newlinelight emitting diodes (LEDs), laser diodes
and in detectors. Electronic devices newlinerealized in GaN operate
at high power and at high temperatures. Recently, it newlinehas
found application in the field of Spintronics with the controlled
doping of newlinetransition metal dopants in GaN. Investigations
have been carried out to study the ferromagnetic newlineproperties
of transition metal (TM) doped wurtzite GaN from first principle
newlinecalculations using Tight Binding Linear Muffin-tin Orbital
(TBLMTO) newlinemethod within the density functional theory. The
structural and optical studies were newlineevaluated using X-ray
diffractometer and Photoluminescence measurements. newlineMagnetic
properties of the synthesized samples have been evaluated with
newlinesuperconducting quantum interface device measurements.
Magnetic properties of the synthesized samples have been
newlineevaluated with superconducting quantum interface device
measurements. The newlineobserved results are correlated with the
theoretical studies. The morphology of these nanostructures
newlinewas studied using high resolution scanning electron
microscope. X-ray newlinediffraction and micro-Raman spectroscopy
measurements confirmed that the newlinegrown GaN nanostructures are
of hexagonal wurtzite structure without any newlineadditional oxide
phase. The emission properties of these nanostructures have
newlinebeen investigated using Photoluminescence. newlineThe
results of these investigations have been published in
newlineinternational journals and also presented in several
national and international newlineconferences newline
newline
Advisors/Committee Members: Kumar, J..
Subjects/Keywords: Gallium nitride; magnetic; ion irradiation;
nanostructure
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
S, M. B. (2014). Investigations on the magnetic properties of doped
gallium nitride ion irradiation studies and nanostructure
growth;. (Thesis). Anna University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/14542
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
S, Munawar Basha. “Investigations on the magnetic properties of doped
gallium nitride ion irradiation studies and nanostructure
growth;.” 2014. Thesis, Anna University. Accessed January 23, 2021.
http://shodhganga.inflibnet.ac.in/handle/10603/14542.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
S, Munawar Basha. “Investigations on the magnetic properties of doped
gallium nitride ion irradiation studies and nanostructure
growth;.” 2014. Web. 23 Jan 2021.
Vancouver:
S MB. Investigations on the magnetic properties of doped
gallium nitride ion irradiation studies and nanostructure
growth;. [Internet] [Thesis]. Anna University; 2014. [cited 2021 Jan 23].
Available from: http://shodhganga.inflibnet.ac.in/handle/10603/14542.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
S MB. Investigations on the magnetic properties of doped
gallium nitride ion irradiation studies and nanostructure
growth;. [Thesis]. Anna University; 2014. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/14542
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Anna University
15.
Suresh kumar V.
Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;.
Degree: Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers, 2015, Anna University
URL: http://shodhganga.inflibnet.ac.in/handle/10603/34219
► Gallium nitride GaN is one of the most promising materials newlineamong group III nitrides because its bandgap of 34 eV makes it the best newlinecandidate…
(more)
▼ Gallium nitride GaN is one of the most promising
materials newlineamong group III nitrides because its bandgap of 34
eV makes it the best newlinecandidate for devices operating in the
blue or UV part of the electromagnetic newlinespectrum GaN is
mainly used in light emitting diodes LEDs laser diodes newlineLDs
ultraviolet detectors colour displays and microwave devices GaN is
newlinethe favourable material system for hightemperature and
highpower newlineelectronic devices newlineGaN nanostructures have
attracted much attention because of their newlinepotential for the
near visible and UV optoelectronic applications GaN
newlinenanostructures are mostly grown by vapourliquidsolid method
MBE and newlineHVPE methods The chemical vapour deposition CVD
technique continues newlineto lead the field of crystalline thin
film technology by exploring new physics newlinematerial science
and fabrication of novel devices newline newline
Reference p.119-133
Advisors/Committee Members: Kumar J.
Subjects/Keywords: gallium nitride; ion irradiation; science and humanities
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APA (6th Edition):
V, S. k. (2015). Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;. (Thesis). Anna University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/34219
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
V, Suresh kumar. “Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;.” 2015. Thesis, Anna University. Accessed January 23, 2021.
http://shodhganga.inflibnet.ac.in/handle/10603/34219.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
V, Suresh kumar. “Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;.” 2015. Web. 23 Jan 2021.
Vancouver:
V Sk. Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;. [Internet] [Thesis]. Anna University; 2015. [cited 2021 Jan 23].
Available from: http://shodhganga.inflibnet.ac.in/handle/10603/34219.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
V Sk. Growth and characterisation of gallium nitride
nanostructures and investigations on the effect of ion irradiation
on mocvd grown gallium nitride epilayers;. [Thesis]. Anna University; 2015. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/34219
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
16.
Christian, George.
Photoluminescence Studies of InGaN/GaN Quantum Well
Structures.
Degree: 2018, University of Manchester
URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:317549
► In this thesis, optical studies of c-plane InGaN/GaN quantum well (QW) structures are presented. The effects of a Si-doped underlayer (UL) on the optical properties…
(more)
▼ In this thesis, optical studies of c-plane
InGaN/GaN quantum well (QW) structures are presented. The effects
of a Si-doped underlayer (UL) on the optical properties of multiple
quantum well (MQW) structures are investigated. The QW
photoluminescence (PL) emission peak energy and radiative
recombination rate decrease and increase respectively with
increasing number of QWs. These observations are attributed to the
increasing net electric field across the MQW structure as the
strength of the surface polarisation field, which acts in the
opposite sense to the piezoelectric polarisation fields across the
QWs, reduces with increasing distance of the UL from the sample
surface. This leads to a reduction in the electron-hole
recombination energy and wavefunction overlap. It is also shown
that the internal quantum efficiency of the MQW structures may
decrease with increasing number of QWs due to the reducing
radiative recombination rate, which could indicate that carrier
losses due to thermionic emission or interface recombination are
mitigated by the inclusion of an UL. Optical studies of single QW
structures containing Si-doped ULs with different net electric
fields across the QW are presented. The net electric field across
the QW is changed by varying the thickness of the GaN cap layer.
The full width at half maximum of the emission peak increases with
increasing net electric field across the QW. This is attributed to
the increasing variation in electron ground state energies due to
the role of the electric field in the localisation of electrons at
quantum well width fluctuations. For one sample, a smaller
Huang-Rhys factor compared to the rest of the samples is
calculated. The non-exponential PL decays detected on the low
energy side of the QW emission peak from this sample are also of a
different shape to the other PL decays detected at all energies for
the other samples. This may be due to the reversal of the net
electric field across these QW regions. Observations of a broad
emission band on the high energy side of single QW structures at
high excited carrier densities are presented. This band occurs in
the carrier density regime at which the efficiency droop is
observed. The emission band is attributed to higher energy weakly
localised or delocalised electron and hole states that are
populated following the saturation of the localised ground states.
PL decay curves detected across this emission band exhibit plateaus
where the PL intensity remains constant until the higher energy
emission has decayed. These are similar to decays observed in
semiconductor quantum dots, which are characteristic of Pauli state
blocking.
Advisors/Committee Members: BINKS, DAVID DJ, Dawson, Philip, Binks, David.
Subjects/Keywords: photoluminescence; gallium nitride; nitrides; quantum well; semiconductor
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APA ·
Chicago ·
MLA ·
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Manager
APA (6th Edition):
Christian, G. (2018). Photoluminescence Studies of InGaN/GaN Quantum Well
Structures. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:317549
Chicago Manual of Style (16th Edition):
Christian, George. “Photoluminescence Studies of InGaN/GaN Quantum Well
Structures.” 2018. Doctoral Dissertation, University of Manchester. Accessed January 23, 2021.
http://www.manchester.ac.uk/escholar/uk-ac-man-scw:317549.
MLA Handbook (7th Edition):
Christian, George. “Photoluminescence Studies of InGaN/GaN Quantum Well
Structures.” 2018. Web. 23 Jan 2021.
Vancouver:
Christian G. Photoluminescence Studies of InGaN/GaN Quantum Well
Structures. [Internet] [Doctoral dissertation]. University of Manchester; 2018. [cited 2021 Jan 23].
Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:317549.
Council of Science Editors:
Christian G. Photoluminescence Studies of InGaN/GaN Quantum Well
Structures. [Doctoral Dissertation]. University of Manchester; 2018. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:317549
University of Colorado
17.
Montague, Joshua R.
As-Grown Gallium Nitride Nanowire Electromechanical Resonators.
Degree: PhD, Physics, 2013, University of Colorado
URL: https://scholar.colorado.edu/phys_gradetds/74
► Technological development in recent years has led to a ubiquity of micro- and nano-scale electromechanical devices. Sensors for monitoring temperature, pressure, mass, etc., are…
(more)
▼ Technological development in recent years has led to a ubiquity of micro- and nano-scale electromechanical devices. Sensors for monitoring temperature, pressure, mass, etc., are now found in nearly all electronic devices at both the industrial and consumer levels. As has been true for integrated circuit electronics, these electromechanical devices have continued to be scaled down in size. For many nanometer-scale structures with large surface-to-volume ratio, dissipation (energy loss) becomes prohibitively large causing a decreasing sensitivity with decreasing sensor size.
In this work,
gallium nitride (GaN) nanowires are investigated as singly-clamped (cantilever) mechanical resonators with typical mechanical quality factors,
Q (equal to the ratio of resonance frequency to peak full-width-at-half-maximum-power) and resonance frequencies, respectively, at or above 30,000, and near 1 MHz. These
Q values {in vacuum at room temperature{ indicate very low levels of dissipation; they are essentially the same as those for bulk quartz crystal resonators that form the basis of simple clocks and mass sensors. The GaN nanowires have lengths and diameters, respectively, of approximately 15 micrometers and hundreds of nanometers. As-grown GaN nanowire
Q values are larger than other similarly-sized, bottom-up, cantilever resonators and this property makes them very attractive for use as resonant sensors.
We demonstrate the capability of detecting sub-monolayer levels of atomic layer deposited (ALD) films, and the robust nature of the GaN nanowires structure that allows for their 'reuse' after removal of such layers. In addition to electron microscope-based measurement techniques, we demonstrate the successful capacitive detection of a single nanowire using microwave homodyne reflectometry. This technique is then extended to allow for simultaneous measurements of large ensembles of GaN nanowires on a single sample, providing statistical information about the distribution of individual nanowire properties. We observe nanowire-to-nanowire variations in the temperature dependence of GaN nanowire resonance frequency and in the observed mechanical dissipation. We also use this ensemble measurement technique to demonstrate unique, very low-loss resonance behavior at low temperatures. The low dissipation (and corresponding large
Q values) observed in as-grown GaN nanowires also provides a unique opportunity for studying fundamental energy loss mechanisms in nano-scale objects. With estimated mass sensitivities on the level of zeptograms (10
-21 g) in a one second averaging time, GaN nanowires may be a significant addition to the field of resonant sensors and worthy of future research and device integration.
Advisors/Committee Members: Charles Rogers, Victor M. Bright, Cindy Regal, Kyle McElroy, Daniel Dessau.
Subjects/Keywords: dissipation; gallium nitride; mems; nanowire; resonator; Physics
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APA (6th Edition):
Montague, J. R. (2013). As-Grown Gallium Nitride Nanowire Electromechanical Resonators. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/74
Chicago Manual of Style (16th Edition):
Montague, Joshua R. “As-Grown Gallium Nitride Nanowire Electromechanical Resonators.” 2013. Doctoral Dissertation, University of Colorado. Accessed January 23, 2021.
https://scholar.colorado.edu/phys_gradetds/74.
MLA Handbook (7th Edition):
Montague, Joshua R. “As-Grown Gallium Nitride Nanowire Electromechanical Resonators.” 2013. Web. 23 Jan 2021.
Vancouver:
Montague JR. As-Grown Gallium Nitride Nanowire Electromechanical Resonators. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Jan 23].
Available from: https://scholar.colorado.edu/phys_gradetds/74.
Council of Science Editors:
Montague JR. As-Grown Gallium Nitride Nanowire Electromechanical Resonators. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/phys_gradetds/74
University of Bristol
18.
Rackauskas, Ben.
The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability.
Degree: PhD, 2019, University of Bristol
URL: http://hdl.handle.net/1983/c126d16b-d8fa-4526-8836-131e6c2bd2ab
► Highly efficient power conversion beyond the capabilities of silicon electronics is required to meet the growing global demand for power and to enable emerging technologies.…
(more)
▼ Highly efficient power conversion beyond the capabilities of silicon electronics is required to meet the growing global demand for power and to enable emerging technologies. The high breakdown field of wide bandgap semiconductors make these materials capable of meeting this demand in a power electronics revolution. Gallium nitride (GaN) is especially suited to this role due to its high electron mobility and its ability to form a high density 2D electron gas, resulting in enhanced efficiency. Compared to silicon, GaN systems can provide more efficient power conversion at higher voltages, all at a fraction of the system size. Despite its promising material properties, a number of research topics remain before GaN technology can be fully exploited. In lateral devices, the substrate is usually grounded so increasing the vertical breakdown voltage of GaN-on-Si epitaxies is required to enable higher voltage devices while maintaining the low production cost associated with the use of silicon substrates. This has been approached from two directions in this thesis. Firstly from a material property perspective, by furthering the understanding of how carbon doping increases the resistivity of GaN. Through a combination of electrical measurements and device simulations, it is shown that carbon in GaN incorporates as donors as well as acceptors and that this self-compensation ratio of donors to acceptors is above 0.4. As the self-compensation ratio determines the material resistivity, it is an essential parameter in device design and future simulation works. Secondly, optimisation of epitaxial resistivity was approached at the device level. It is shown through electrical measurements that the resistivity of the epitaxy is reduced after processing Ti/Al based Ohmic contacts. These sub-contact leakage paths are further studied through a novel use of the quasi-static capacitance-voltage technique to reveal these paths extend up to 1.6 μm, all the way to the superlattice strain relief layers. The existence of these leakage paths is widely unknown and being aware of their impact is an important step forward for buffer design and accurate device simulation. Vertical GaN-on-GaN devices are desired over lateral devices for their improved thermal performance, superior breakdown characteristics and reduced peak surface fields. The primary research efforts are focused on optimising vertical leakage and edge termination. The reverse leakage in vertical pn diodes is studied in the time domain and reveals the first evidence of impurity band conduction. The model required to explain the results also demonstrates the ability of charged point defects to control the conductivity of dislocations. This new understanding of the leakage dynamics could influence the way leakage is managed in future device designs. The reliability of these devices is also a topic of interest as qualification of this emerging vertical GaN technology is required before commercialisation. The mean time to failure of these vertical diodes was evaluated by adapting existing…
Subjects/Keywords: 530; Gallium Nitride; Reliability; Leakage mechanisms
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Rackauskas, B. (2019). The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability. (Doctoral Dissertation). University of Bristol. Retrieved from http://hdl.handle.net/1983/c126d16b-d8fa-4526-8836-131e6c2bd2ab
Chicago Manual of Style (16th Edition):
Rackauskas, Ben. “The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability.” 2019. Doctoral Dissertation, University of Bristol. Accessed January 23, 2021.
http://hdl.handle.net/1983/c126d16b-d8fa-4526-8836-131e6c2bd2ab.
MLA Handbook (7th Edition):
Rackauskas, Ben. “The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability.” 2019. Web. 23 Jan 2021.
Vancouver:
Rackauskas B. The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability. [Internet] [Doctoral dissertation]. University of Bristol; 2019. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/1983/c126d16b-d8fa-4526-8836-131e6c2bd2ab.
Council of Science Editors:
Rackauskas B. The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability. [Doctoral Dissertation]. University of Bristol; 2019. Available from: http://hdl.handle.net/1983/c126d16b-d8fa-4526-8836-131e6c2bd2ab
19.
Johansson, Linus.
Evaluation of graphene as a transparent electrode in GaN-based LEDs by PECVD synthesis of graphene directly on GaN.
Degree: Physics, 2016, Umeå University
URL: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-120731
► A transparent conductive electrode (TCE) is an important component in many of our modern optoelectronic devices like photovoltaics, light emitting diodes and touch screens.…
(more)
▼ A transparent conductive electrode (TCE) is an important component in many of our modern optoelectronic devices like photovoltaics, light emitting diodes and touch screens. These devices require good current injection and spreading as well as a high transparency. In this thesis we explore the use of graphene as an alternative to the current widely used indium tin oxide (ITO) as TCE in gallium nitride (GaN) based light emitting diodes (LEDs). Monolayer crystalline graphene can be produced on copper foils using chemical vapor deposition (CVD), where metals (especially copper) has a catalysing effect on the formation of graphene. However, transfer of graphene from copper foils is not suitable for an industrial scale and it results in a poor contact with the target substrate. We investigate the possibility of directly integrating graphene on GaN-based LEDs by using plasma-enhanced chemical vapor deposition (PECVD). We try to obtain the optimal conditions under these catalyst-free circumstances and propose a recipe adapted for the setup that we used. We will also study ideas of using a metal (we tried copper and nickel) to assist the direct growth that could help to increase the fraction of sp2 carbon bonds and reduce the sheet resistance. The metals are evaporated onto our samples either before or after we grow a carbon film to either assist the growth or rearrange the carbon respectively. The focus was not on trying to optimize the conditions for one metal treatment but rather to briefly explore multiple methods to find a suitable path for further studies. The direct grown pristine carbon films shows indications from Raman measurements of being nanocrystalline graphene with a sheet resistance ranging from about 20-50 kΩ/sq having a transmittance of approximately 96 % at 550 nm. A transmittance at this level is closely related to the value of an ideal monolayer graphene, which indicates that our carbon films could be close to one atom in thickness while being visually homogeneous and complete in coverage. Due to the use of a temperature close to the melting point of copper we struggled to keep the assisting copper from evaporating too fast or staying homogeneous after the treatment. Nickel has a higher melting temperature, but it appears as if this metal might be diffusing into the GaN substrate which changes the properties of both the GaN and carbon film. Even though the metal treatments that we tested did not provide any noticeable improvements, there is need for further investigations to obtain suitable treatment conditions. We suggest that the treatments involving copper are a more promising path to pursue as nickel seem to cause unavoidable intermixing problems.
Subjects/Keywords: PECVD; graphene; transparent electrode; gallium nitride; LED
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APA ·
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MLA ·
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Export
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APA (6th Edition):
Johansson, L. (2016). Evaluation of graphene as a transparent electrode in GaN-based LEDs by PECVD synthesis of graphene directly on GaN. (Thesis). Umeå University. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-120731
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Johansson, Linus. “Evaluation of graphene as a transparent electrode in GaN-based LEDs by PECVD synthesis of graphene directly on GaN.” 2016. Thesis, Umeå University. Accessed January 23, 2021.
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-120731.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Johansson, Linus. “Evaluation of graphene as a transparent electrode in GaN-based LEDs by PECVD synthesis of graphene directly on GaN.” 2016. Web. 23 Jan 2021.
Vancouver:
Johansson L. Evaluation of graphene as a transparent electrode in GaN-based LEDs by PECVD synthesis of graphene directly on GaN. [Internet] [Thesis]. Umeå University; 2016. [cited 2021 Jan 23].
Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-120731.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Johansson L. Evaluation of graphene as a transparent electrode in GaN-based LEDs by PECVD synthesis of graphene directly on GaN. [Thesis]. Umeå University; 2016. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-120731
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Hong Kong University of Science and Technology
20.
Zou, Xinbo.
Growth, Fabrication and characterization of InGaN/GaN-based blue, green and yellow LEDs on Si with nanotechnology.
Degree: 2013, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-8142
;
https://doi.org/10.14711/thesis-b1214705
;
http://repository.ust.hk/ir/bitstream/1783.1-8142/1/th_redirect.html
► InGaN/GaN-based light emitting diodes (LEDs) grown on Si have generated intensiveresearch interest due to silicon’s low cost, large size availability and good thermal conductivity. However,…
(more)
▼ InGaN/GaN-based light emitting diodes (LEDs) grown on Si have generated intensiveresearch interest due to silicon’s low cost, large size availability and good thermal conductivity. However, GaN grown on Si normally suffers from large dislocation density and tensile stress due to the huge mismatch in the lattice constant and thermal expansion coefficient between GaN and Si. This thesis focuses on developing high-quality and crack-free InGaN/GaN-based blue, green and yellow LEDs with embedded SiO2 nanorods. GaN buffers were firstly optimized using a source flow ratio modulation method and an AlN/AlGaN superlattice interlayer. After optimization, crystalline quality, surface morphology and stress status were all improved. Moreover, light output power (LOP) was improved by 66% for InGaN/GaN blue LEDs. To further enhance the internal and external quantum efficiencies, high density SiO2 nanorods with an average diameter of less than 400 nm were fabricated on 2 μm thick GaN buffers and embedded into LED structures through nanoscale epitaxial lateral overgrowth. Two simple and non-lithographic methods for SiO2 nanorod fabrication were developed and compared in this work. With SiO2 nanorods surface coverage of 30%, 5 μm thick crack-free InGaN/GaN-based blue LEDs were grown with smooth surfaces. The LOP was raised by 40% compared to those without nanocomponents. The LED structures with embedded SiO2 nanorods were also extended to emit longer wavelength to fill the “green gap”. For 505 nm green LEDs, the optical power was as high as 0.65 mW at 20 mA. Moreover, for the first time, yellow InGaN/GaN MQW LEDs on Si substrates were demonstrated whose LOP and peak wavelength were 31 μW and 565 nm at 20 mA current injection. Low temperature characteristics of green and yellow LEDs were also described and discussed. In the last section of this thesis, a method to remove light absorptive Si substrates and fabricate vertical LEDs was described, in which the LOP was enhanced by 30% over planar LEDs on Si.
Subjects/Keywords: Light emitting diodes
; Nanostructured materials
; Gallium nitride
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APA ·
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Manager
APA (6th Edition):
Zou, X. (2013). Growth, Fabrication and characterization of InGaN/GaN-based blue, green and yellow LEDs on Si with nanotechnology. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-8142 ; https://doi.org/10.14711/thesis-b1214705 ; http://repository.ust.hk/ir/bitstream/1783.1-8142/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Zou, Xinbo. “Growth, Fabrication and characterization of InGaN/GaN-based blue, green and yellow LEDs on Si with nanotechnology.” 2013. Thesis, Hong Kong University of Science and Technology. Accessed January 23, 2021.
http://repository.ust.hk/ir/Record/1783.1-8142 ; https://doi.org/10.14711/thesis-b1214705 ; http://repository.ust.hk/ir/bitstream/1783.1-8142/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Zou, Xinbo. “Growth, Fabrication and characterization of InGaN/GaN-based blue, green and yellow LEDs on Si with nanotechnology.” 2013. Web. 23 Jan 2021.
Vancouver:
Zou X. Growth, Fabrication and characterization of InGaN/GaN-based blue, green and yellow LEDs on Si with nanotechnology. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2013. [cited 2021 Jan 23].
Available from: http://repository.ust.hk/ir/Record/1783.1-8142 ; https://doi.org/10.14711/thesis-b1214705 ; http://repository.ust.hk/ir/bitstream/1783.1-8142/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Zou X. Growth, Fabrication and characterization of InGaN/GaN-based blue, green and yellow LEDs on Si with nanotechnology. [Thesis]. Hong Kong University of Science and Technology; 2013. Available from: http://repository.ust.hk/ir/Record/1783.1-8142 ; https://doi.org/10.14711/thesis-b1214705 ; http://repository.ust.hk/ir/bitstream/1783.1-8142/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Hong Kong University of Science and Technology
21.
Yuan, Li.
Process modeling and device technology of GaN normally-off power transistors.
Degree: 2011, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-7195
;
https://doi.org/10.14711/thesis-b1146196
;
http://repository.ust.hk/ir/bitstream/1783.1-7195/1/th_redirect.html
► The wide bandgap GaN-based transistors are attractive for power electronics applications owing to the superior intrinsic properties of the materials. In addition to the breakdown…
(more)
▼ The wide bandgap GaN-based transistors are attractive for power electronics applications owing to the superior intrinsic properties of the materials. In addition to the breakdown electric-field that is one order of magnitude higher than the mainstream semiconductor silicon, GaN-based heterostructrues (e.g. AlGaN/GaN) enhanced by spontaneous and piezoelectric polarization effects can yield a two-dimensional electron gas (2DEG) channel with a high sheet charge concentration and high electron mobility, both of which lead to low ON-state resistance. On the other hand, the high density 2DEG also presents the conventional AlGaN/GaN high electron mobility transistors (HEMTs) as depletion-mode transistors with a negative threshold voltage (Vth). For simpler circuit configuration and inherent fail-safe operation, normally-off GaN based HEMTs with positive threshold voltage are highly desired in modern power electronics systems. This thesis is focused on the process modeling and device technology of normally-off GaN power transistors. A process based on fluorine plasma ion implantation has been recently developed for achieving a robust control of the threshold voltage of AlGaN/GaN HEMTs, and is emerging as one of the most promising technologies for normally-off GaN power devices. To understand the underlying physical mechanisms of this process and also provide tools for process optimization, an atomistic hybrid molecular dynamics (MD)/kinetic Monte Carlo (KMC) model is developed for modeling the implantation and the subsequent annealing/diffusion behavior of the fluorine ions in AlGaN/GaN heterostructures. The MD simulation reveals the F distribution profiles and the corresponding defect profiles. Most importantly, the potential energy profiles of fluorine ions in the III-nitride material system are calculated for the first time, and the results fundamentally explained the stability of fluorine ions in AlGaN/GaN heterostructrues. Based on the results from the MD simulation, the diffusion process is modeled with KMC method, and the modeling results are validated by the secondary-ion-mass-spectrum (SIMS) measurement. The buffer leakage current is a common challenge being faced by the existing technologies of normally-off GaN power transistors due to the lack of high-quality blocking junctions in the leakage current path. To address this issue, a novel AlGaN/GaN metal-2DEG tunnel junction field-effect transistor (TJ-FET) is proposed and experimentally demonstrated in this work. The TJ-FET, when realized in AlGaN/GaN HEMT structure, delivers desirable features including normally-off operation (Vth = + 1.35 V), low leakage current (~10 pA/mm) and high on/off current ratio (1010). A maximum ON-state drain current density as high as 320 mA/mm has been obtained. The leakage current is effectively suppressed by the source Schottky junction that is naturally reverse biased in the OFF-state. The threshold voltage controlling scheme of TJ-FET is also fundamentally different from that of the conventional HEMTs, adding another degree of…
Subjects/Keywords: Power transistors
; Gallium nitride
; Semiconductors – Materials
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APA (6th Edition):
Yuan, L. (2011). Process modeling and device technology of GaN normally-off power transistors. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-7195 ; https://doi.org/10.14711/thesis-b1146196 ; http://repository.ust.hk/ir/bitstream/1783.1-7195/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Yuan, Li. “Process modeling and device technology of GaN normally-off power transistors.” 2011. Thesis, Hong Kong University of Science and Technology. Accessed January 23, 2021.
http://repository.ust.hk/ir/Record/1783.1-7195 ; https://doi.org/10.14711/thesis-b1146196 ; http://repository.ust.hk/ir/bitstream/1783.1-7195/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Yuan, Li. “Process modeling and device technology of GaN normally-off power transistors.” 2011. Web. 23 Jan 2021.
Vancouver:
Yuan L. Process modeling and device technology of GaN normally-off power transistors. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2011. [cited 2021 Jan 23].
Available from: http://repository.ust.hk/ir/Record/1783.1-7195 ; https://doi.org/10.14711/thesis-b1146196 ; http://repository.ust.hk/ir/bitstream/1783.1-7195/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Yuan L. Process modeling and device technology of GaN normally-off power transistors. [Thesis]. Hong Kong University of Science and Technology; 2011. Available from: http://repository.ust.hk/ir/Record/1783.1-7195 ; https://doi.org/10.14711/thesis-b1146196 ; http://repository.ust.hk/ir/bitstream/1783.1-7195/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Hong Kong University of Science and Technology
22.
Lu, Jun-yong.
Mechanical characterization of GaN epitaxial thin films.
Degree: 2011, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-7360
;
https://doi.org/10.14711/thesis-b1155692
;
http://repository.ust.hk/ir/bitstream/1783.1-7360/1/th_redirect.html
► In this work, epitaxial GaN thin films were mechanically characterized. Residual stresses of the films were systematically investigated with micro-Raman spectroscopy and their elastic-plastic properties…
(more)
▼ In this work, epitaxial GaN thin films were mechanically characterized. Residual stresses of the films were systematically investigated with micro-Raman spectroscopy and their elastic-plastic properties were studied by conducting nanoindentation tests at temperatures of 23 °C, 100 °C, and 180 °C. A series of works were carried out to investigate the mechanical stress- or strain-induced change in Raman spectrum of the GaN films. A home-made four-point bending device allows us to in-situ measure the uniaxial stress- or strain-induced change in Raman spectrum. The phonon frequency shifts were observed in-situ under four-pint bending and the experimental data were analyzed successfully. The present work developed a state-of-the-art biaxial stress modulation method, which was aided with the microelectromechanical system (MEMS) patterning technique and finite element analysis, to examine more thoroughly the change in Raman spectrum of GaN films under biaxial stress or strain. Based on the fact that residual stress is relaxed in a coin-shaped island, and the smaller the island is, the much more severe the residual stress will be relieved, we fabricated coin-shaped islands on an originally stressed GaN film and had the island radius ranging from xx μm to xx μm to modulate the biaxial stress. With this approach, the phonon deformation potentials (PDPs) of GaN were accurately and reliably determined to be 3.43 cm-1/GPa and 2.34 cm-1/GPa for EH2 and A1 (LO) phonons, respectively. With the determined PDPs, the residual stresses in various GaN films were convincingly characterized with the micro-Raman mapping technique. The GaN thin films were also characterized mechanically by using the nanoindentation technique. The elastic modulus of the GaN films were evaluated at temperatures of 23 °C, 100 °C, and 180 °C with the “O-P method” on unloading curve and the Hertzian contact analysis on the initial stage of loading curve. The experimental results show that the reduced modulus of GaN decreased with temperature from around 240 GPa (23 °C) to around 140 GPa (180 ºC) according to the “O-P method”, or from 270 GPa (23 °C) to around 230 GPa (180 ºC) according to the Hertzian analysis. The results might suggest that the Hertzian analysis could produce more reliable results in spite of the thermal drift accumulated at a high temperature. This is because the Hertzian analysis uses the initial experimental data which suffer less influence from the thermal drift, while the unloading curve bears more influence from the thermal drift. This research investigated the first pop-in event systematically. The first pop-in event in force-displacement curves reflects the elastic-plastic deformation transition of GaN films. A large number of data on the first pop-in event allowed statistical analysis. Based on Schuh et al.’s model, the statistical analysis yielded the activation energy of 849.76±35.85 meV, the activation volume of 10.76±1.61 Å3 and the frequency factor of 4.23×1021 m-3s-1. The shear strength, defined as the critical maximum shear…
Subjects/Keywords: Thin films – Mechanical properties
; Gallium nitride
; Epitaxy
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APA ·
Chicago ·
MLA ·
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CSE |
Export
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Manager
APA (6th Edition):
Lu, J. (2011). Mechanical characterization of GaN epitaxial thin films. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-7360 ; https://doi.org/10.14711/thesis-b1155692 ; http://repository.ust.hk/ir/bitstream/1783.1-7360/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lu, Jun-yong. “Mechanical characterization of GaN epitaxial thin films.” 2011. Thesis, Hong Kong University of Science and Technology. Accessed January 23, 2021.
http://repository.ust.hk/ir/Record/1783.1-7360 ; https://doi.org/10.14711/thesis-b1155692 ; http://repository.ust.hk/ir/bitstream/1783.1-7360/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lu, Jun-yong. “Mechanical characterization of GaN epitaxial thin films.” 2011. Web. 23 Jan 2021.
Vancouver:
Lu J. Mechanical characterization of GaN epitaxial thin films. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2011. [cited 2021 Jan 23].
Available from: http://repository.ust.hk/ir/Record/1783.1-7360 ; https://doi.org/10.14711/thesis-b1155692 ; http://repository.ust.hk/ir/bitstream/1783.1-7360/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lu J. Mechanical characterization of GaN epitaxial thin films. [Thesis]. Hong Kong University of Science and Technology; 2011. Available from: http://repository.ust.hk/ir/Record/1783.1-7360 ; https://doi.org/10.14711/thesis-b1155692 ; http://repository.ust.hk/ir/bitstream/1783.1-7360/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Tennessee – Knoxville
23.
Bouler, Douglas Wayne, III.
GAN-BASED POINT-OF-LOAD CONVERTERS FOR DATA CENTER APPLICATIONS.
Degree: MS, Electrical Engineering, 2018, University of Tennessee – Knoxville
URL: https://trace.tennessee.edu/utk_gradthes/5341
► The growth of the information technology sector has increased demand for high-density, high-efficiency point-of-load (POL) converters. As industry continues to demand an increase in server…
(more)
▼ The growth of the information technology sector has increased demand for high-density, high-efficiency point-of-load (POL) converters. As industry continues to demand an increase in server processing power, high-current operation presents challenges to designing high-efficiency POL converters. Increased conduction and overlap losses induce significant power losses in high-power modes. The introduction of
Gallium-
Nitride (GaN) switching devices and the implementation of zero-current-switching (ZCS) topologies for POL applications have the potential to improve converter efficiency while maintaining or surpassing the industrial power density standard. This thesis addresses the challenges presented by high-current operation by demonstrating an accurate power loss model of the quasi-resonant zero-current-switching (QR-ZCS) buck converter and presents a comparison between the synchronous buck and QR-ZCS buck in a 5-1.8 V POL application.
Advisors/Committee Members: Daniel Costinett, Benjamin Blalock, Leon Tolbert.
Subjects/Keywords: Gallium-Nitride; GaN; POL; power density
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APA (6th Edition):
Bouler, Douglas Wayne, I. (2018). GAN-BASED POINT-OF-LOAD CONVERTERS FOR DATA CENTER APPLICATIONS. (Thesis). University of Tennessee – Knoxville. Retrieved from https://trace.tennessee.edu/utk_gradthes/5341
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Bouler, Douglas Wayne, III. “GAN-BASED POINT-OF-LOAD CONVERTERS FOR DATA CENTER APPLICATIONS.” 2018. Thesis, University of Tennessee – Knoxville. Accessed January 23, 2021.
https://trace.tennessee.edu/utk_gradthes/5341.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Bouler, Douglas Wayne, III. “GAN-BASED POINT-OF-LOAD CONVERTERS FOR DATA CENTER APPLICATIONS.” 2018. Web. 23 Jan 2021.
Vancouver:
Bouler, Douglas Wayne I. GAN-BASED POINT-OF-LOAD CONVERTERS FOR DATA CENTER APPLICATIONS. [Internet] [Thesis]. University of Tennessee – Knoxville; 2018. [cited 2021 Jan 23].
Available from: https://trace.tennessee.edu/utk_gradthes/5341.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Bouler, Douglas Wayne I. GAN-BASED POINT-OF-LOAD CONVERTERS FOR DATA CENTER APPLICATIONS. [Thesis]. University of Tennessee – Knoxville; 2018. Available from: https://trace.tennessee.edu/utk_gradthes/5341
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Bristol
24.
Rackauskas, Ben.
The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability.
Degree: PhD, 2019, University of Bristol
URL: https://research-information.bris.ac.uk/en/studentTheses/c126d16b-d8fa-4526-8836-131e6c2bd2ab
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787682
► Highly efficient power conversion beyond the capabilities of silicon electronics is required to meet the growing global demand for power and to enable emerging technologies.…
(more)
▼ Highly efficient power conversion beyond the capabilities of silicon electronics is required to meet the growing global demand for power and to enable emerging technologies. The high breakdown field of wide bandgap semiconductors make these materials capable of meeting this demand in a power electronics revolution. Gallium nitride (GaN) is especially suited to this role due to its high electron mobility and its ability to form a high density 2D electron gas, resulting in enhanced efficiency. Compared to silicon, GaN systems can provide more efficient power conversion at higher voltages, all at a fraction of the system size. Despite its promising material properties, a number of research topics remain before GaN technology can be fully exploited. In lateral devices, the substrate is usually grounded so increasing the vertical breakdown voltage of GaN-on-Si epitaxies is required to enable higher voltage devices while maintaining the low production cost associated with the use of silicon substrates. This has been approached from two directions in this thesis. Firstly from a material property perspective, by furthering the understanding of how carbon doping increases the resistivity of GaN. Through a combination of electrical measurements and device simulations, it is shown that carbon in GaN incorporates as donors as well as acceptors and that this self-compensation ratio of donors to acceptors is above 0.4. As the self-compensation ratio determines the material resistivity, it is an essential parameter in device design and future simulation works. Secondly, optimisation of epitaxial resistivity was approached at the device level. It is shown through electrical measurements that the resistivity of the epitaxy is reduced after processing Ti/Al based Ohmic contacts. These sub-contact leakage paths are further studied through a novel use of the quasi-static capacitance-voltage technique to reveal these paths extend up to 1.6 μm, all the way to the superlattice strain relief layers. The existence of these leakage paths is widely unknown and being aware of their impact is an important step forward for buffer design and accurate device simulation. Vertical GaN-on-GaN devices are desired over lateral devices for their improved thermal performance, superior breakdown characteristics and reduced peak surface fields. The primary research efforts are focused on optimising vertical leakage and edge termination. The reverse leakage in vertical pn diodes is studied in the time domain and reveals the first evidence of impurity band conduction. The model required to explain the results also demonstrates the ability of charged point defects to control the conductivity of dislocations. This new understanding of the leakage dynamics could influence the way leakage is managed in future device designs. The reliability of these devices is also a topic of interest as qualification of this emerging vertical GaN technology is required before commercialisation. The mean time to failure of these vertical diodes was evaluated by adapting existing…
Subjects/Keywords: 530; Gallium Nitride; Reliability; Leakage mechanisms
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APA ·
Chicago ·
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APA (6th Edition):
Rackauskas, B. (2019). The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability. (Doctoral Dissertation). University of Bristol. Retrieved from https://research-information.bris.ac.uk/en/studentTheses/c126d16b-d8fa-4526-8836-131e6c2bd2ab ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787682
Chicago Manual of Style (16th Edition):
Rackauskas, Ben. “The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability.” 2019. Doctoral Dissertation, University of Bristol. Accessed January 23, 2021.
https://research-information.bris.ac.uk/en/studentTheses/c126d16b-d8fa-4526-8836-131e6c2bd2ab ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787682.
MLA Handbook (7th Edition):
Rackauskas, Ben. “The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability.” 2019. Web. 23 Jan 2021.
Vancouver:
Rackauskas B. The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability. [Internet] [Doctoral dissertation]. University of Bristol; 2019. [cited 2021 Jan 23].
Available from: https://research-information.bris.ac.uk/en/studentTheses/c126d16b-d8fa-4526-8836-131e6c2bd2ab ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787682.
Council of Science Editors:
Rackauskas B. The characterisation of gallium nitride devices for power electronic applications : leakage mechanisms and device reliability. [Doctoral Dissertation]. University of Bristol; 2019. Available from: https://research-information.bris.ac.uk/en/studentTheses/c126d16b-d8fa-4526-8836-131e6c2bd2ab ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787682
Rutgers University
25.
Jumaah, Omar Dhannoon, 1983-.
Experimental and numerical study on manufacturing gallium nitride thin films in MOCVD process.
Degree: PhD, Mechanical and Aerospace Engineering, 2019, Rutgers University
URL: https://rucore.libraries.rutgers.edu/rutgers-lib/61775/
► Gallium nitride (GaN) thin film is an attractive material for manufacturing optoelectronic device applications due to its wide band-gap and superb optoelectronic performance. The reliability…
(more)
▼ Gallium nitride (GaN) thin film is an attractive material for manufacturing optoelectronic device applications due to its wide band-gap and superb optoelectronic performance. The reliability and durability of the devices depend on the quality of thin films. Metal-organic chemical vapor deposition (MOCVD) process is a common technique used to fabricate high-quality GaN thin films. The deposition rate and uniformity of thin films are manipulated by controlling operating conditions and reactor geometry configurations. In this study, the epitaxial growth of GaN thin films on sapphire substrates (AL2O3) was carried out in two commercial MOCVD systems, a vertical rotating disk MOCVD reactor, and a close-coupled showerhead MOCVD reactor. Material characterizations have been done using Atomic Force Microscopy (AFM), X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and Raman scattering to examine the surface morphology and crystal quality of GaN thin films. The growth rate and uniformity of GaN thin films are simulated based on a three-dimensional computational fluid dynamics (CFD) model. Transport phenomena and chemical kinetics of the GaN growth process are performed using a reduced chemistry model, which contains 17 gas phase, and 8 surface species participating in 17 gas phase and 17 surface reactions. Numerical simulation of the single wafer and multi-wafers reactors have performed. A comprehensive study of the influence of operating variables, including rotation rate of the susceptor, susceptor temperature, inlet velocity, the reactor pressure, and precursor concentration ratio, on the GaN growth process is carried out. Operating parameters that have significant effects on the growth rate and uniformity of GaN thin films are identified. The reactor pressure and flow rate of trimethylgallium (TMG) have a significant effect on the deposition rate. A high-quality thin film is obtained when pure H2 is used as a carrier gas. The high flow rate of pure N2 gas enhances the growth of GaN thin films at high reactor pressure. However, it decreases the uniformity of the GaN thin film and promotes carbon contaminations. Thus, using an appropriate mixture of H2 and N2 as a carrier can improve the deposition rate and quality of GaN thin films. The inlet design has a significant effect on improving the reactant species utilization and increases the growth rate. The proper distance between the inlet and the susceptor aids to decrease the temperature gradient and improve the stability of the flow above the rotating susceptor.
The optimization of GaN deposition rate and uniformity in the MOCVD process have represented in a surrogate model. Surrogate-based optimization is an effective technique to alleviate expensive computation experiments with fewer sample points. The response surface from simulation data with minimum error variance estimation is generated using the Kriging method. The optimization of GaN deposition is performed as a deterministic problem, without taking into consideration the uncertain input parameters and…
Advisors/Committee Members: Jaluria, Yogesh (chair), Mazzeo, Aaron (internal member), Shan, Jerry (internal member), Birnie, Dunbar (outside member), School of Graduate Studies.
Subjects/Keywords: Gallium nitride; Metal organic chemical vapor deposition
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APA (6th Edition):
Jumaah, Omar Dhannoon, 1. (2019). Experimental and numerical study on manufacturing gallium nitride thin films in MOCVD process. (Doctoral Dissertation). Rutgers University. Retrieved from https://rucore.libraries.rutgers.edu/rutgers-lib/61775/
Chicago Manual of Style (16th Edition):
Jumaah, Omar Dhannoon, 1983-. “Experimental and numerical study on manufacturing gallium nitride thin films in MOCVD process.” 2019. Doctoral Dissertation, Rutgers University. Accessed January 23, 2021.
https://rucore.libraries.rutgers.edu/rutgers-lib/61775/.
MLA Handbook (7th Edition):
Jumaah, Omar Dhannoon, 1983-. “Experimental and numerical study on manufacturing gallium nitride thin films in MOCVD process.” 2019. Web. 23 Jan 2021.
Vancouver:
Jumaah, Omar Dhannoon 1. Experimental and numerical study on manufacturing gallium nitride thin films in MOCVD process. [Internet] [Doctoral dissertation]. Rutgers University; 2019. [cited 2021 Jan 23].
Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/61775/.
Council of Science Editors:
Jumaah, Omar Dhannoon 1. Experimental and numerical study on manufacturing gallium nitride thin films in MOCVD process. [Doctoral Dissertation]. Rutgers University; 2019. Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/61775/
King Abdullah University of Science and Technology
26.
Ibrahim, Youssef H.
Low Damage, High Anisotropy Inductively Coupled Plasma for Gallium Nitride based Devices.
Degree: 2013, King Abdullah University of Science and Technology
URL: http://hdl.handle.net/10754/292971
► Group III-nitride semiconductors possess unique properties, which make them versatile materials for suiting many applications. Structuring vertical and exceptionally smooth GaN profiles is crucial for…
(more)
▼ Group III-nitride semiconductors possess unique properties, which make them versatile materials for suiting many applications. Structuring vertical and exceptionally smooth GaN profiles is crucial for efficient optical device operation. The processing requirements for laser devices and ridge waveguides are stringent as compared to LEDs and other electronic devices. Due to the strong bonding and chemically inert nature of GaN, dry etching becomes a critical fabrication step. The surface morphology and facet etch angle are analyzed using SEM and AFM measurements. The influence of different mask materials is also studied including Ni as well as a SiO2 and resist bilayer. The high selectivity Ni Mask is found to produce high sidewall angles ~79°. Processing parameters are optimized for both the mask material and GaN in order to achieve a highly anisotropic, smooth profile, without resorting to additional surface treatment steps. An optimizing a SF6/O2 plasma etch process resulted in smooth SiO2 mask sidewalls. The etch rate and GaN surface roughness dependence on the RF power was also examined. Under a low 2mTorr pressure, the RF and ICP power were optimized to 150W and 300W respectively, such that a smooth GaN morphology and sidewalls was achieved with reduced ion damage. The The AFM measurements of the etched GaN surface indicate a low RMS roughness ranging from 4.75 nm to 7.66 nm.
Subjects/Keywords: Gallium; Nitride; Inductively; Coupled; Plasma; Facets
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APA ·
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APA (6th Edition):
Ibrahim, Y. H. (2013). Low Damage, High Anisotropy Inductively Coupled Plasma for Gallium Nitride based Devices. (Thesis). King Abdullah University of Science and Technology. Retrieved from http://hdl.handle.net/10754/292971
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Ibrahim, Youssef H. “Low Damage, High Anisotropy Inductively Coupled Plasma for Gallium Nitride based Devices.” 2013. Thesis, King Abdullah University of Science and Technology. Accessed January 23, 2021.
http://hdl.handle.net/10754/292971.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Ibrahim, Youssef H. “Low Damage, High Anisotropy Inductively Coupled Plasma for Gallium Nitride based Devices.” 2013. Web. 23 Jan 2021.
Vancouver:
Ibrahim YH. Low Damage, High Anisotropy Inductively Coupled Plasma for Gallium Nitride based Devices. [Internet] [Thesis]. King Abdullah University of Science and Technology; 2013. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/10754/292971.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Ibrahim YH. Low Damage, High Anisotropy Inductively Coupled Plasma for Gallium Nitride based Devices. [Thesis]. King Abdullah University of Science and Technology; 2013. Available from: http://hdl.handle.net/10754/292971
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Edinburgh
27.
Anderson, Tom Harper.
Optoelectronic simulation of nonhomogeneous solar cells.
Degree: PhD, 2016, University of Edinburgh
URL: http://hdl.handle.net/1842/25892
► This thesis investigates the possibility of enhancing the efficiency of thin film solar cells by including periodic material nonhomogeneities in combination with periodically corrugated back…
(more)
▼ This thesis investigates the possibility of enhancing the efficiency of thin film solar cells by including periodic material nonhomogeneities in combination with periodically corrugated back reflectors. Two different types of solar cell are investigated; p-i-n junctions solar cells made from alloys of hydrogenated amorphous silicon (a-Si:H) (containing either carbon or germanium), and Schottky barrier junction solar cells made from alloys of indium gallium nitride (InξGa1-ξN). Material nonhomogeneities are produced by varying the fractions of the constituent elements of the alloys. For example, by varying the content of carbon or germanium in the a-Si:H alloys, semiconductors with bandgaps ranging from 1:3 eV to 1:95 eV can be produced. Changing the bandgap alters both the optical and electrical properties of the material so this necessitates the use of coupled optical and electrical models. To date, the majority of solar cell simulations either prioritise the electrical portion of the simulation or they prioritise the optical portion of the simulation. In this thesis, a coupled optoelectronic model, developed using COMSOL Multiphysics®, was used to simulate solar cells: a two-dimensional finite-element optical model, which solved Maxwell's equations throughout the solar cells, was used to calculate the absorption of incident sunlight; and a finite-element electrical drift-diffusion transport model, either one- or two-dimensional depending on the symmetries of the problem, was used to calculate the steady state current densities throughout the solar cells under external voltage biases. It is shown that a periodically corrugated back reflector made from silver can increase efficiency of an a-Si:H alloy single p-i-n junction solar cell by 9:9% compared to a baseline design, while for a triple junction the improvement is a relatively meagre 1:8%. It is subsequently shown that the efficiency of these single p-i-n junction solar cells with a back reflector can be further increased by the inclusion of material nonhomogeneities, and that increasing the nonhomogeneity progressively increases efficiency, especially in thicker solar cells. In the case of InξGa1-ξN Schottky barrier junction solar cells, the gains are shown to be even greater. An overall increase in efficiency of up to 26:8% over a baseline design is reported.
Subjects/Keywords: 621.36; thin film solar cells; p-i-n junctions; hydrogenated amorphous silicon; a-Si:H; Schottky barrier junction solar cells; indium gallium nitride; bandgap; Maxwell's equations
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APA (6th Edition):
Anderson, T. H. (2016). Optoelectronic simulation of nonhomogeneous solar cells. (Doctoral Dissertation). University of Edinburgh. Retrieved from http://hdl.handle.net/1842/25892
Chicago Manual of Style (16th Edition):
Anderson, Tom Harper. “Optoelectronic simulation of nonhomogeneous solar cells.” 2016. Doctoral Dissertation, University of Edinburgh. Accessed January 23, 2021.
http://hdl.handle.net/1842/25892.
MLA Handbook (7th Edition):
Anderson, Tom Harper. “Optoelectronic simulation of nonhomogeneous solar cells.” 2016. Web. 23 Jan 2021.
Vancouver:
Anderson TH. Optoelectronic simulation of nonhomogeneous solar cells. [Internet] [Doctoral dissertation]. University of Edinburgh; 2016. [cited 2021 Jan 23].
Available from: http://hdl.handle.net/1842/25892.
Council of Science Editors:
Anderson TH. Optoelectronic simulation of nonhomogeneous solar cells. [Doctoral Dissertation]. University of Edinburgh; 2016. Available from: http://hdl.handle.net/1842/25892
University of Utah
28.
Anderson, Kathy Perkins Jenkins.
Characterizing organometallic-vapor-phase-epitaxy-grown indium gallium nitride islands on gallium nitride for light emitting diode applications.
Degree: MS, Materials Science & Engineering, 2011, University of Utah
URL: http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/541/rec/445
► The indium-gallium-nitride on gallium-nitride (InGaN/GaN) materials system is a promising candidate for providing a high intensity, high efficiency solution to the yet unsolved problem of…
(more)
▼ The indium-gallium-nitride on gallium-nitride (InGaN/GaN) materials system is a promising candidate for providing a high intensity, high efficiency solution to the yet unsolved problem of solid state lighting in the range of 550 to 590 nm, a.k.a the Green Gap. The bandgap of InGaN/GaN spans the visual spectrum, making it tunable for emission at any wavelength. The lattice constant mismatch and resulting strain at the heterojunction induces a miscibility gap that enables spontaneous self-assembly of indium-rich nm-scale islands during Stranski-Krastanov growth of the InGaN active layer of the Light Emitting Diode (LED). These islands serve as quantum discs, confining excitons, and increasing internal quantum efficiency. InGaN/GaN/Al2O3 samples from Cao Group Inc. were interrupted after the InGaN growth step of the Organometallic Vapor-Phase Epitaxy (OMVPE) process and analyzed using Atomic Force Microscopy (AFM), High Resolution Scanning Electron Microscopy (HRSEM), Transmission Electron Microscopy (TEM), Raman, and Photoluminescence (PL) spectroscopies. Results show inhomogeneities in light emission and structure as well as conductivity.Coherence, strain, and the presence of indium were all confirmed through TEM and Energy Dispersive X-ray spectroscopy (EDX). Islands (3-10nm in height) and pits (1-4nm deep) cluster in patches with a marbled pattern. Islands tend to be found most predominantly at the edges or the bottom of pits, suggesting indium-rich island growth is preferred along the edges of structures of high surface area, where strain from lattice mismatch is most compensated by surface area. Despite coherence, Fast Fourier Transform (FFT) reciprocal space patterns show lattice spacing and possibly the crystal structure type itself differ between island and subisland areas. The difference between island emission energy and the energy required to excite carriers is greater than expected. PL peak energy and Raman shift frequency test results were used to estimate island indium composition. Polarization of emission was observed, though was unexpected due to the InGaN having been grown on c-plane GaN which should result in isotropic biaxial strain and a valence band configuration that does not lend to bifurcating probabilities of polarization. Near-Field PL testing was performed, also with unexpected results.
Subjects/Keywords: InGaN; Island; LED; Quantum dots; Self assembly; Strain; Indium gallium nitride islands; Gallium nitride
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APA (6th Edition):
Anderson, K. P. J. (2011). Characterizing organometallic-vapor-phase-epitaxy-grown indium gallium nitride islands on gallium nitride for light emitting diode applications. (Masters Thesis). University of Utah. Retrieved from http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/541/rec/445
Chicago Manual of Style (16th Edition):
Anderson, Kathy Perkins Jenkins. “Characterizing organometallic-vapor-phase-epitaxy-grown indium gallium nitride islands on gallium nitride for light emitting diode applications.” 2011. Masters Thesis, University of Utah. Accessed January 23, 2021.
http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/541/rec/445.
MLA Handbook (7th Edition):
Anderson, Kathy Perkins Jenkins. “Characterizing organometallic-vapor-phase-epitaxy-grown indium gallium nitride islands on gallium nitride for light emitting diode applications.” 2011. Web. 23 Jan 2021.
Vancouver:
Anderson KPJ. Characterizing organometallic-vapor-phase-epitaxy-grown indium gallium nitride islands on gallium nitride for light emitting diode applications. [Internet] [Masters thesis]. University of Utah; 2011. [cited 2021 Jan 23].
Available from: http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/541/rec/445.
Council of Science Editors:
Anderson KPJ. Characterizing organometallic-vapor-phase-epitaxy-grown indium gallium nitride islands on gallium nitride for light emitting diode applications. [Masters Thesis]. University of Utah; 2011. Available from: http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/541/rec/445
Virginia Commonwealth University
29.
Li, Xing.
Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes.
Degree: PhD, Engineering, 2012, Virginia Commonwealth University
URL: https://doi.org/10.25772/V6FM-0B17
;
https://scholarscompass.vcu.edu/etd/395
► In the past decade, GaN-based nitrides have had a considerable impact in solid state lighting and high speed high power devices. InGaN-based LEDs have been…
(more)
▼ In the past decade, GaN-based nitrides have had a considerable impact in solid state lighting and high speed high power devices. InGaN-based LEDs have been widely used for all types of displays in TVs, computers, cell phones, etc. More and more high power LEDs have also been introduced in general lighting market. Once widely used, such LEDs could lead to the decrease of worldwide electrical consumption for lighting by more than 50% and reduce total electricity consumption by > 10%.
However, there are still challenges for current state-of-the art InGaN-based LEDs, including ‘efficiency droop’ issues that cause output power quenching at high current injection levels (> 100 A/cm2). In this dissertation, approaches were investigated to address the major issues related to state-of-the-art
nitride LEDs, in particular related to (1) efficiency droop investigations on m-plane and c-plane LEDs: enhanced matrix elements in m-plane LEDs and smaller hole effective mass favors the hole transport across the active region so that m-plane LEDs exhibit 30% higher quantum efficiency and negligible efficiency droop at high injection levels compared to c-plane counterparts; (2) engineering of InGaN active layers for achieving high quantum efficiency and minimal efficiency droop: lower and thinner InGaN barrier enhance hole transport as well as improves the quantum efficiencies at injection levels; (3) double-heterostructure (DH) active regions: various thicknesses were also investigated in order to understand the electron and hole recombination mechanism. We also present that using multi-thin DH active regions is a superior approach to enhance the quantum efficiency compared with simply increasing the single DH thickness or the number of quantum wells (QWs, 2 nm-thick) in multi-QW (MQW) LED structures due to the better material quality and higher density of states. Additionally, increased thickness of stair-case electron injectors (SEIs) has been demonstrated to greatly mitigate electron overflow without sacrificing material quality of the active regions. Finally, approaches to enhance light extraction efficiency including using Ga doped ZnO as the p-GaN contact layer to improve light extraction as well as current spreading was introduced.
Advisors/Committee Members: Hadis Morkoc.
Subjects/Keywords: gallium nitride; indium gallium nitride; light emitting diodes; efficiency droop; quantum efficiency; Engineering
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APA (6th Edition):
Li, X. (2012). Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes. (Doctoral Dissertation). Virginia Commonwealth University. Retrieved from https://doi.org/10.25772/V6FM-0B17 ; https://scholarscompass.vcu.edu/etd/395
Chicago Manual of Style (16th Edition):
Li, Xing. “Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes.” 2012. Doctoral Dissertation, Virginia Commonwealth University. Accessed January 23, 2021.
https://doi.org/10.25772/V6FM-0B17 ; https://scholarscompass.vcu.edu/etd/395.
MLA Handbook (7th Edition):
Li, Xing. “Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes.” 2012. Web. 23 Jan 2021.
Vancouver:
Li X. Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes. [Internet] [Doctoral dissertation]. Virginia Commonwealth University; 2012. [cited 2021 Jan 23].
Available from: https://doi.org/10.25772/V6FM-0B17 ; https://scholarscompass.vcu.edu/etd/395.
Council of Science Editors:
Li X. Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes. [Doctoral Dissertation]. Virginia Commonwealth University; 2012. Available from: https://doi.org/10.25772/V6FM-0B17 ; https://scholarscompass.vcu.edu/etd/395
Texas State University – San Marcos
30.
Hancock, Bobby Logan.
Characterization of Devices and Materials for Gallium Nitride and Diamond Thermal Management Applications.
Degree: PhD, Materials Science, Engineering, and Commercialization, 2016, Texas State University – San Marcos
URL: https://digital.library.txstate.edu/handle/10877/6966
► As trends progress toward higher power applications in GaN-based electronic and photonic devices, the issue of self-heating becomes a prominent concern. This is especially the…
(more)
▼ As trends progress toward higher power applications in GaN-based electronic and photonic devices, the issue of self-heating becomes a prominent concern. This is especially the case for high-brightness light-emitting diodes (LEDs) and high electron mobility transistors (HEMTs), where the bulk of power dissipation occurs within a small (sub-micron) region resulting in highly localized temperature rises during operation. Monitoring these thermal effects becomes critical as they significantly affect performance, reliability, and overall device lifetime. In response to these issues, diamond grown by chemical vapor deposition (CVD) has emerged as a promising material in III-
nitride thermal management as a heat-spreading substrate due to its exceptional thermal conductivity. This work is aimed toward the characterization of self-heating and thermal management technologies in GaN electronic and photonic devices and their materials. The two main components of this dissertation include assessing self-heating in these devices through direct measurement of temperature rises in high-power LEDs and GaN HEMTs and qualifying thermal management approaches through the characterization of thermal conductivity and material quality in CVD diamond and its incorporation into GaN device layers. The purpose of this work is to further the understanding of thermal effects in III-
nitride materials as well as provide useful contributions to the development of future thermal management technologies in GaN device applications.
Advisors/Committee Members: Holtz, Mark W. (advisor), Piner, Edwin L. (committee member), Zakhidov, Alex (committee member), Myers, Thomas H. (committee member), Wetzel, Jeff (committee member).
Subjects/Keywords: Gallium Nitride; Diamond; Raman; Photoluminescence; CVD; LED; HEMT; Gallium nitride; Electronics – Research
Record Details
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Record Details
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APA ·
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MLA ·
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CSE |
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APA (6th Edition):
Hancock, B. L. (2016). Characterization of Devices and Materials for Gallium Nitride and Diamond Thermal Management Applications. (Doctoral Dissertation). Texas State University – San Marcos. Retrieved from https://digital.library.txstate.edu/handle/10877/6966
Chicago Manual of Style (16th Edition):
Hancock, Bobby Logan. “Characterization of Devices and Materials for Gallium Nitride and Diamond Thermal Management Applications.” 2016. Doctoral Dissertation, Texas State University – San Marcos. Accessed January 23, 2021.
https://digital.library.txstate.edu/handle/10877/6966.
MLA Handbook (7th Edition):
Hancock, Bobby Logan. “Characterization of Devices and Materials for Gallium Nitride and Diamond Thermal Management Applications.” 2016. Web. 23 Jan 2021.
Vancouver:
Hancock BL. Characterization of Devices and Materials for Gallium Nitride and Diamond Thermal Management Applications. [Internet] [Doctoral dissertation]. Texas State University – San Marcos; 2016. [cited 2021 Jan 23].
Available from: https://digital.library.txstate.edu/handle/10877/6966.
Council of Science Editors:
Hancock BL. Characterization of Devices and Materials for Gallium Nitride and Diamond Thermal Management Applications. [Doctoral Dissertation]. Texas State University – San Marcos; 2016. Available from: https://digital.library.txstate.edu/handle/10877/6966
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