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University of Oklahoma
1.
Booth, Donald.
DETECTION OF "TRILOBITE" AND "BUTTERFLY" RYDBERG MOLECULES IN CESIUM WITH KILODEBYE DIPOLE MOMENTS.
Degree: PhD, 2015, University of Oklahoma
URL: http://hdl.handle.net/11244/14244 
► The detection and characterization of two classes of ultralong-range Rydberg molecules known as "trilobite" and "butterfly" molecules is presented. These molecules are a subset of…
(more)
▼ The detection and characterization of two classes of ultralong-range Rydberg molecules known as "trilobite" and "butterfly" molecules is presented. These molecules are a subset of a class of Rydberg molecules which asymptotically consist of a Rydberg atom and a ground state atom. The trilobite and butterfly molecules have giant, body-fixed permanent dipole moments on the order of 1000 Debye. The two classes of molecules are distinguished by the relative dominance of the s-wave and p-wave electron scattering. Spectra for (nS
1/2 + 6S
1/2)
3 Sigma molecules, where n = 37, 39 and 40 and measurements of the Stark broadenings of selected trilobite states in Cs due to the application of a constant external electric field are presented. Additionally, measurements of spectra and Stark splittings for p-wave dominated (nS
1/2 + 6S
1/2)
3 Pi molecules, where n = 31 and 32 are presented. Computational work on Rydberg pair interactions is also discussed.
Advisors/Committee Members: Shaffer, James (advisor), Shi, Zhisheng (committee member), Murphy, Sheena (committee member), Parker, Gregory (committee member), Abraham, Eric (committee member).
Subjects/Keywords: Physics, Atomic.; Physics, Molecular.; Physics, Optics.
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APA (6th Edition):
Booth, D. (2015). DETECTION OF "TRILOBITE" AND "BUTTERFLY" RYDBERG MOLECULES IN CESIUM WITH KILODEBYE DIPOLE MOMENTS. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/14244
Chicago Manual of Style (16th Edition):
Booth, Donald. “DETECTION OF "TRILOBITE" AND "BUTTERFLY" RYDBERG MOLECULES IN CESIUM WITH KILODEBYE DIPOLE MOMENTS.” 2015. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/14244.
MLA Handbook (7th Edition):
Booth, Donald. “DETECTION OF "TRILOBITE" AND "BUTTERFLY" RYDBERG MOLECULES IN CESIUM WITH KILODEBYE DIPOLE MOMENTS.” 2015. Web. 01 Mar 2021.
Vancouver:
Booth D. DETECTION OF "TRILOBITE" AND "BUTTERFLY" RYDBERG MOLECULES IN CESIUM WITH KILODEBYE DIPOLE MOMENTS. [Internet] [Doctoral dissertation]. University of Oklahoma; 2015. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/14244.
Council of Science Editors:
Booth D. DETECTION OF "TRILOBITE" AND "BUTTERFLY" RYDBERG MOLECULES IN CESIUM WITH KILODEBYE DIPOLE MOMENTS. [Doctoral Dissertation]. University of Oklahoma; 2015. Available from: http://hdl.handle.net/11244/14244
University of Oklahoma
2.
Lotfi, Hossein.
Interband Cascade Structures for Infrared Photodetectors and Thermophotovoltaic Devices.
Degree: PhD, 2016, University of Oklahoma
URL: http://hdl.handle.net/11244/47113
► Interband cascade (IC) devices are a family of quantum engineered heterostructures that include: IC lasers (ICLs), IC infrared photodetectors (ICIPs) and IC thermophotovoltaic (ICTPV) devices.…
(more)
▼ Interband cascade (IC) devices are a family of quantum engineered heterostructures that include: IC lasers (ICLs), IC infrared photodetectors (ICIPs) and IC thermophotovoltaic (ICTPV) devices. In these structures, the transport of carriers across different stages is made possible by the type-II broken-gap band alignment between InAs and GaSb. Many shortcomings in conventional single absorber narrow-bandgap devices, such as short carrier lifetime and limited diffusion length (particularly at high temperatures) can be addressed by a multiple-stage architecture. While multiple photons need to be absorbed to output one electron in a multi-stage detector or photovoltaic cell, the multiple-stage architecture has some big benefits, especially at high temperatures and long wavelengths. The multiple excitations (depending on the number of stages) of each electron in an ICIP result in lower noise (higher signal-to-noise) than conventional single-stage detectors with thick absorbers. Furthermore, by keeping individual absorbers shorter than the minority carrier diffusion length most of the photogenerated carriers can be collected. This efficient collection of photogenerated carriers along with the high open-circuit voltages lead to high conversion efficiencies in ICTPV devices. The theoretical and experimental exploration of these properties of ICIPs and ICTPV devices are the main focus of this dissertation.
Design and characterization of ICIPs in different bands including short- through very long-wavelength IR are discussed in detail. It is shown that a multiple-stage detector has superior performance over a single-stage detector at high temperatures.
In contrast to single-stage detectors, in ICIPs high-frequency bandwidths can be achieved with no compromise on the device sensitivity. The high-frequency modeling and characterization of ICIPs reveal gigahertz bandwidth (~1.3 GHz) with high detectivity (˃1E9 cm.Hz1/2/W) for three-stage mid-IR ICIPs at 300 K. A comparative study of time domain characteristics (i.e., eye diagrams) of single-stage detectors and ICIPs (with the total absorber thickness equal to that of the single-stage devices) confirmed the higher bandwidth and shorter fall and rise times in ICIPs.
The unidirectional flow of carriers in IC lasers makes their structure feasible for infrared detection. Therefore, it is possible to realize monolithically integrated lasers and detectors on a single chip. Since the detector section is edge-illuminated in these bi-functional devices, detectivities higher than 1E10 cm.Hz1/2/W were estimated for these detectors at room temperature (RT). High-detectivity and high-speed ICIPs along with low power consumption ICLs make monolithically integrated IC lasers and detectors a practical choice for compact spectrometers and lab-on-a-chip devices.
Two sets of ICTPV devices (Eg < 0.5 eV) were investigated to understand the influence of number of stages/absorber thickness on the TPV cells performance. Efficiencies up to ~10% were achieved in three-stage ICTPVs with 0.41 eV bandgap.…
Advisors/Committee Members: Yang, Rui Q. (advisor), Johnson, Matthew B. (committee member), Shi, Zhisheng (committee member), Cruz, J. R. (committee member), Sellers, Ian R. (committee member).
Subjects/Keywords: Optoelectronics; Infrared; Photodetectors; Thermophotovoltaic
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APA (6th Edition):
Lotfi, H. (2016). Interband Cascade Structures for Infrared Photodetectors and Thermophotovoltaic Devices. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/47113
Chicago Manual of Style (16th Edition):
Lotfi, Hossein. “Interband Cascade Structures for Infrared Photodetectors and Thermophotovoltaic Devices.” 2016. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/47113.
MLA Handbook (7th Edition):
Lotfi, Hossein. “Interband Cascade Structures for Infrared Photodetectors and Thermophotovoltaic Devices.” 2016. Web. 01 Mar 2021.
Vancouver:
Lotfi H. Interband Cascade Structures for Infrared Photodetectors and Thermophotovoltaic Devices. [Internet] [Doctoral dissertation]. University of Oklahoma; 2016. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/47113.
Council of Science Editors:
Lotfi H. Interband Cascade Structures for Infrared Photodetectors and Thermophotovoltaic Devices. [Doctoral Dissertation]. University of Oklahoma; 2016. Available from: http://hdl.handle.net/11244/47113
University of Oklahoma
3.
Ghani, Muhammad.
Optimization of a High-Energy X-Ray Inline Phase Sensitive Imaging System for Diagnosis of Breast Cancer.
Degree: PhD, 2018, University of Oklahoma
URL: http://hdl.handle.net/11244/299328
► Breast cancer screening modalities have received constant research attention that are mainly focused on their abilities to detect cancer at an early stage while reducing…
(more)
▼ Breast cancer screening modalities have received constant research attention that are mainly focused on their abilities to detect cancer at an early stage while reducing the risks of harmful radiation dose delivered to the patient. As a result, numerous advancements have been made over the last two decades which include the introduction of digital mammography (DM) and digital breast tomosynthesis (DBT). Numerous clinical trials have demonstrated the decrease in mortality rates by employing these modalities. Significant research attention remains focused on investigating methods for further improving the detection capabilities and reducing the radiation dose. The conventional x-ray imaging technique relies on the attenuation characteristics of a tissue to produce imaging contrast. However, the similar attenuation characteristics of normal and malignant breast tissue present a challenge in differentiating between them using conventional x-ray imaging. The current technique for providing higher image quality involves the introduction of anti-scatter grids and operating the x-ray tubes at much lower x-ray energies as compared to the other radiography fields, both of which results in an increased radiation dose. The current method for providing higher image quality involves utilizing anti-scatter grids and operating at much lower x-ray energies than other radiography fields, both of which result in an increased radiation dose. Phase sensitive imaging is an emerging technique, which relies not only on attenuation coefficients but also the effects produced by x-ray phase shift coefficients. Within the diagnostic energy range, it has been estimated that the phase shift coefficients of a breast tissue are at least 2-3 orders of magnitude larger than their attenuation coefficients. Thus, this technique holds the potential to increase the x-ray energy and remove the grid without compromising the image quality, which could potentially reduce the patient dose. The inline phase sensitive approach involves the simplest implementation—provided that the imaging system is spatially coherent — as it does not involve the introduction of any optical element between the object and detector. Preclinical studies with the inline phase sensitive imaging technique at the same energy as conventional imaging have indicated the ability to reduce the radiation dose without negatively impacting the diagnostic capabilities. However, there are some existing challenges that have prevented this technique in its clinical implementation. Responding to the challenges, an inline phase sensitive imaging prototype has been developed in the advanced biomedical imaging laboratory. The goal of the research presented in this dissertation comprises a thorough investigation in optimizing a high energy phase sensitive imaging prototype efficiently in terms of its geometric and operating parameters. Once optimized, the imaging performance of this phase sensitive x-ray imaging prototype is going to be compared with the commercial digital mammography and digital…
Advisors/Committee Members: Liu, Hong (advisor), Ahmad, Ramadan (committee member), Zheng, Bin (committee member), Shi, Zhisheng (committee member), Havlicek, Joseph (committee member).
Subjects/Keywords: x-ray phase contrast imaging; phase retrieval; breast cancer imaging; phase sensitive imaging
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APA (6th Edition):
Ghani, M. (2018). Optimization of a High-Energy X-Ray Inline Phase Sensitive Imaging System for Diagnosis of Breast Cancer. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/299328
Chicago Manual of Style (16th Edition):
Ghani, Muhammad. “Optimization of a High-Energy X-Ray Inline Phase Sensitive Imaging System for Diagnosis of Breast Cancer.” 2018. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/299328.
MLA Handbook (7th Edition):
Ghani, Muhammad. “Optimization of a High-Energy X-Ray Inline Phase Sensitive Imaging System for Diagnosis of Breast Cancer.” 2018. Web. 01 Mar 2021.
Vancouver:
Ghani M. Optimization of a High-Energy X-Ray Inline Phase Sensitive Imaging System for Diagnosis of Breast Cancer. [Internet] [Doctoral dissertation]. University of Oklahoma; 2018. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/299328.
Council of Science Editors:
Ghani M. Optimization of a High-Energy X-Ray Inline Phase Sensitive Imaging System for Diagnosis of Breast Cancer. [Doctoral Dissertation]. University of Oklahoma; 2018. Available from: http://hdl.handle.net/11244/299328
University of Oklahoma
4.
Jiang, Yuchao.
High-performance InAs-based interband cascade lasers.
Degree: PhD, 2016, University of Oklahoma
URL: http://hdl.handle.net/11244/34604
► Currently, there are only two types of mid-infrared lasers that are capable of continuous-wave (CW) operation above room temperature: quantum cascade (QC) lasers and interband…
(more)
▼ Currently, there are only two types of mid-infrared lasers that are capable of continuous-wave (CW) operation above room temperature: quantum cascade (QC) lasers and interband cascade (IC) lasers. Both of them share the cascade feature for carrier recycling. The most successful QC lasers, based on the inter-subband transition and the well-established InGaAs/InAlAs/InP material system, are able to deliver several watts of optical power. In contrast, IC lasers, based on the interband transition and the unique InAs/GaSb/AlSb type-II broken-bandgap material system, have the threshold power density more than an order of magnitude lower than that of QC lasers (e.g., 0.3 kW/cm2 vs. 11 kW/cm2). As a result, IC lasers become a better solution for low-power applications in the mid-infrared region.
GaSb-based IC lasers have achieved the best performance around 3.7 μm with a threshold current density as low as 100 A/cm2 at 300 K. However, their waveguide cladding layers, consisting of thick InAs/AlSb superlattice, have a low thermal conductivity and are challenging to grow by molecular beam epitaxy. These problems become more severe at longer lasing wavelengths due to the requirement of thicker cladding layers. InAs-based IC lasers, utilizing highly doped InAs as the optical cladding layer, have been developed to address these issues. The goal of this dissertation is to use modeling and experiments to explore several aspects of InAs-based IC lasers, including far-field patterns, high-temperature operation, long-wavelength operation, wide-tunability, and single frequency mode operation.
The beam quality is critical for the laser application. The higher-order spatial modes naturally appear when the laser ridge is wider than the lasing wavelength in the medium. For InAs-based IC lasers with a thin top cladding layer, the top contact configuration can have a major influence on the spatial modes, which are observed in the measurement of far-field patterns. The physical origin is identified by waveguide modeling based on an effective index method.
Radical design innovations, including “shortened injector” and “carrier rebalancing,” have significantly improved the performance of both GaSb-based and InAs-based IC lasers. Furthermore, a hybrid waveguide, consisting of an inner cladding layer with InAs/AlSb superlattice and an outer cladding layer with highly doped InAs, has significantly increased the modal gain of InAs-based IC lasers. As a result, CW operations above room temperature have been achieved at wavelengths of 4.6~4.8 μm. The threshold current density, 247 A/cm2 at 300 K in pulsed mode, is the lowest ever reported among the mid-infrared semiconductor lasers at similar wavelengths. The pulsed operating temperature is as high as 377 K.
Long-wavelength operations are vigorously explored. With the hybrid waveguide mentioned above, the lasing temperature reaches 324 K at a wavelength of 6.4 μm. Further design improvement and optimization are presented. In addition, the lasing wavelength is extended to 11.2 μm at 130 K.…
Advisors/Committee Members: Yang, Rui (advisor), Santos, Michael (committee member), Shi, Zhisheng (committee member), Johnson, Matthew (committee member), Sluss, James (committee member).
Subjects/Keywords: semiconductor lasers; interband cascade; mid-infrared
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APA (6th Edition):
Jiang, Y. (2016). High-performance InAs-based interband cascade lasers. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/34604
Chicago Manual of Style (16th Edition):
Jiang, Yuchao. “High-performance InAs-based interband cascade lasers.” 2016. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/34604.
MLA Handbook (7th Edition):
Jiang, Yuchao. “High-performance InAs-based interband cascade lasers.” 2016. Web. 01 Mar 2021.
Vancouver:
Jiang Y. High-performance InAs-based interband cascade lasers. [Internet] [Doctoral dissertation]. University of Oklahoma; 2016. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/34604.
Council of Science Editors:
Jiang Y. High-performance InAs-based interband cascade lasers. [Doctoral Dissertation]. University of Oklahoma; 2016. Available from: http://hdl.handle.net/11244/34604
University of Oklahoma
5.
Shen, Yu-Ting.
SEARCH FOR ELECTROWEAK PRODUCTION OF SUPERSYMMETRIC STATES IN NON-UNIVERSAL HIGGS MASS MODEL WITH TWO EXTRA PARAMETERS COMPRESSED SCENARIO WITH THE ATLAS DETECTOR.
Degree: PhD, 2018, University of Oklahoma
URL: http://hdl.handle.net/11244/299774
► The ATLAS and CMS collaborations announced the discovery of the Higgs boson in July 2012, completing the particle content of the Standard Model. Although the…
(more)
▼ The ATLAS and CMS collaborations announced the discovery of the Higgs boson in July 2012, completing the particle content of the Standard Model.
Although the Standard Model is a great triumph, it is not considered to be the complete theory of particle physics.
Among the newly-developed theories, Supersymmetry (SUSY) is one of the most promising ones.
SUSY predicts the existence of supersymmetric partner particles and it is one of the best-motivated extensions of the space-time symmetry of particle interactions.
There are supersymmetric partner particles associated with each SM particles in which the spin differs by 1/2.
This dissertation focuses on a search for electroweak production of supersymmetric particles with compressed mass spectra in the final states with exactly two low-momentum leptons and missing transverse momentum.
The proton-proton collision data is recorded by the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to 36.1~{\ifb} of integrated luminosity at √{s} = 13~{\TeV}.
Events with same-flavor and opposite electric charge lepton pairs are selected.
The data are found to be consistent with the Standard Model prediction.
Results are interpreted using the non-universal Higgs mass model with two extra parameters (NUHM2) with small mass differences between the masses of produced supersymmetric particles.
Upper limits of the cross-section at 95% confidence level are set for the NUHM2 model as a function of the universal gaugino mass m
1/2.
Advisors/Committee Members: Skubic, Patrick (advisor), Strauss, Michael (committee member), Baer, Howie (committee member), Watson, Deborah (committee member), Shi, Zhisheng (committee member).
Subjects/Keywords: SUSY; NUHM2; supersymmetry; ATLAS; compressed
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APA (6th Edition):
Shen, Y. (2018). SEARCH FOR ELECTROWEAK PRODUCTION OF SUPERSYMMETRIC STATES IN NON-UNIVERSAL HIGGS MASS MODEL WITH TWO EXTRA PARAMETERS COMPRESSED SCENARIO WITH THE ATLAS DETECTOR. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/299774
Chicago Manual of Style (16th Edition):
Shen, Yu-Ting. “SEARCH FOR ELECTROWEAK PRODUCTION OF SUPERSYMMETRIC STATES IN NON-UNIVERSAL HIGGS MASS MODEL WITH TWO EXTRA PARAMETERS COMPRESSED SCENARIO WITH THE ATLAS DETECTOR.” 2018. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/299774.
MLA Handbook (7th Edition):
Shen, Yu-Ting. “SEARCH FOR ELECTROWEAK PRODUCTION OF SUPERSYMMETRIC STATES IN NON-UNIVERSAL HIGGS MASS MODEL WITH TWO EXTRA PARAMETERS COMPRESSED SCENARIO WITH THE ATLAS DETECTOR.” 2018. Web. 01 Mar 2021.
Vancouver:
Shen Y. SEARCH FOR ELECTROWEAK PRODUCTION OF SUPERSYMMETRIC STATES IN NON-UNIVERSAL HIGGS MASS MODEL WITH TWO EXTRA PARAMETERS COMPRESSED SCENARIO WITH THE ATLAS DETECTOR. [Internet] [Doctoral dissertation]. University of Oklahoma; 2018. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/299774.
Council of Science Editors:
Shen Y. SEARCH FOR ELECTROWEAK PRODUCTION OF SUPERSYMMETRIC STATES IN NON-UNIVERSAL HIGGS MASS MODEL WITH TWO EXTRA PARAMETERS COMPRESSED SCENARIO WITH THE ATLAS DETECTOR. [Doctoral Dissertation]. University of Oklahoma; 2018. Available from: http://hdl.handle.net/11244/299774
University of Oklahoma
6.
Guan, Ye.
REACTIONS OF NITRIC OXIDE, NITROSOALKANES WITH GROUP 8 & 9 METALLOPORPHYRINS AND HEME PROTEINS.
Degree: PhD, 2015, University of Oklahoma
URL: http://hdl.handle.net/11244/15493
► This dissertation describes the interactions of nitric oxide (NO) and C-nitrosoalkanes (RNO) with group 8 and 9 metalloporphyrins and heme proteins. The goal of this…
(more)
▼ This dissertation describes the interactions of nitric oxide (NO) and C-nitrosoalkanes (RNO) with group 8 and 9 metalloporphyrins and heme proteins. The goal of this research is to provide new information on the coordination chemistry of NO and NO-related compounds.
Advisors/Committee Members: Richter-Addo, George B. (advisor), Liu, Shaorong (committee member), West, Ann H. (committee member), Yang, Zhibo (committee member), Shi, Zhisheng (committee member).
Subjects/Keywords: Chemistry; inorganic; biochemistry
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APA (6th Edition):
Guan, Y. (2015). REACTIONS OF NITRIC OXIDE, NITROSOALKANES WITH GROUP 8 & 9 METALLOPORPHYRINS AND HEME PROTEINS. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/15493
Chicago Manual of Style (16th Edition):
Guan, Ye. “REACTIONS OF NITRIC OXIDE, NITROSOALKANES WITH GROUP 8 & 9 METALLOPORPHYRINS AND HEME PROTEINS.” 2015. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/15493.
MLA Handbook (7th Edition):
Guan, Ye. “REACTIONS OF NITRIC OXIDE, NITROSOALKANES WITH GROUP 8 & 9 METALLOPORPHYRINS AND HEME PROTEINS.” 2015. Web. 01 Mar 2021.
Vancouver:
Guan Y. REACTIONS OF NITRIC OXIDE, NITROSOALKANES WITH GROUP 8 & 9 METALLOPORPHYRINS AND HEME PROTEINS. [Internet] [Doctoral dissertation]. University of Oklahoma; 2015. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/15493.
Council of Science Editors:
Guan Y. REACTIONS OF NITRIC OXIDE, NITROSOALKANES WITH GROUP 8 & 9 METALLOPORPHYRINS AND HEME PROTEINS. [Doctoral Dissertation]. University of Oklahoma; 2015. Available from: http://hdl.handle.net/11244/15493
University of Oklahoma
7.
Cheng, Yang.
Quantum dots for Photovoltaic Applications.
Degree: PhD, 2017, University of Oklahoma
URL: http://hdl.handle.net/11244/52730
► During the past century, impacts of climate change on both natural and human systems have been observed worldwide. Numerous scientific investigations suggest a strong correlation…
(more)
▼ During the past century, impacts of climate change on both natural and human systems have been observed worldwide. Numerous scientific investigations suggest a strong correlation between the global warming and greenhouse gas (GHG) emissions. CO2 emission accounts for 78% of the GHG emissions, and 35% of this CO2 comes from electricity generation. Reduction of GHG emission from the electricity generation would therefore be beneficial to decrease global warming.
As a renewable energy source, in comparison with conventional fossil fuels, solar energy has limitless supply, is accessible in most geographic locations, and is much cleaner. Currently, solar energy is economically viable in areas where the infrastructure is limited, or the GHG emissions are restricted by policy. To further facilitate the ubiquitous deployment of solar energy on a tera-watt utility scale, further increases in power conversion efficiency and reductions in cost are still required of solar cell technology.
Third generation solar cells are emerging solar cell technologies, which are predicted to operate beyond the Shockley-Queisser limit for single bandgap cells. Nanostructured materials are under investigation as potential candidates for next generation photovoltaic technologies. In this dissertation, one type of nanostructured material, semiconductor quantum dots (QDs), were studied for their potential applications for next-generation photovoltaics.
Epitaxial self-assembled InAs/GaAsSb QD solar cells are investigated for applications as intermediate band solar cells. These systems have a theoretical efficiency of ∼ 50% with a simple single junction design. Two sets of optical InAs/GaAsSb QD samples grown by Molecular Beam Epitaxy (MBE), one set with various InAs deposition thicknesses, and the other set with different percentages of Sb composition in the barrier, were studied to determine the optimal growth conditions in terms of QD density and uniformity. A deposition thickness of 3 monolayers (ML) and 14% Sb matrix composition were shown to yield uniform QDs with the highest QD density ~ 3.5 X 10
11 /cm
2 and a quasi-flat valance band alignment.
Four p-i-n GaAs solar cells with different intrinsic region designs were then grown by MBE. An unusually large reduction of the Voc and a complex behavior of Jsc were both observed. A detailed experimental investigation of these devices supports the hypothesis that thermal activation of defects or ionization of impurities in the lattice induces a transition from that dominated by radiative recombination to non-radiative processes. This results in a quenching of the photoluminescence and electroluminescence intensity and a decrease the z-factor from 2 to 1, with increasing temperature. The 1.1% lattice mismatch between the GaAs substrate and GaAsSb matrix contributes to the defect formation, which serves as the main limitation of the performance of InAs/GaAsSb quantum dot solar cells presented in this work.
PbS/ZnO colloidal QD solar cells are investigated for thin film…
Advisors/Committee Members: Sellers, Ian (advisor), Mullen, Kieran (committee member), Santos, Michael (committee member), Abraham, Eric (committee member), Shi, Zhisheng (committee member).
Subjects/Keywords: Photovoltaic; Quantum dot; Solar cell
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APA (6th Edition):
Cheng, Y. (2017). Quantum dots for Photovoltaic Applications. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/52730
Chicago Manual of Style (16th Edition):
Cheng, Yang. “Quantum dots for Photovoltaic Applications.” 2017. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/52730.
MLA Handbook (7th Edition):
Cheng, Yang. “Quantum dots for Photovoltaic Applications.” 2017. Web. 01 Mar 2021.
Vancouver:
Cheng Y. Quantum dots for Photovoltaic Applications. [Internet] [Doctoral dissertation]. University of Oklahoma; 2017. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/52730.
Council of Science Editors:
Cheng Y. Quantum dots for Photovoltaic Applications. [Doctoral Dissertation]. University of Oklahoma; 2017. Available from: http://hdl.handle.net/11244/52730
University of Oklahoma
8.
Li, Donghui.
MBE GROWTH AND CHARACTERIZATION OF Pb-SALT SEMICONDUCTORS FOR MID-INFRARED DETECTOR AND LASER APPLICATION.
Degree: PhD, 2009, University of Oklahoma
URL: http://hdl.handle.net/11244/318915
► Lead salt mid-infrared optoelectronic devices are fabricated on various substrates. Several other research works include: (1) Edge-emitting infrared lasers on BaF2 (110) substrates. A method…
(more)
▼ Lead salt mid-infrared optoelectronic devices are fabricated on various substrates. Several other research works include: (1) Edge-emitting infrared lasers on BaF2 (110) substrates. A method of substrate transfer from a BaF2 substrate to a copper heat-sink is developed. Pulsed photoluminescence (PL) measurements are conducted with help of Fourier transform infrared (FTIR) spectroscopy method during every single step of device processing. (2) Mid-infrared detectors on silicon (111) substrates. Single-element PbSnSe infrared detectors have been made on CaF2 /Si (111) heterostructures; I-V measurement is accomplished on these detectors.
Advisors/Committee Members: Shi, Zhisheng (advisor).
Subjects/Keywords: Molecular beam epitaxy; Quantum wells; Solid-state lasers; Laser materials; Semiconductors
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APA (6th Edition):
Li, D. (2009). MBE GROWTH AND CHARACTERIZATION OF Pb-SALT SEMICONDUCTORS FOR MID-INFRARED DETECTOR AND LASER APPLICATION. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/318915
Chicago Manual of Style (16th Edition):
Li, Donghui. “MBE GROWTH AND CHARACTERIZATION OF Pb-SALT SEMICONDUCTORS FOR MID-INFRARED DETECTOR AND LASER APPLICATION.” 2009. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/318915.
MLA Handbook (7th Edition):
Li, Donghui. “MBE GROWTH AND CHARACTERIZATION OF Pb-SALT SEMICONDUCTORS FOR MID-INFRARED DETECTOR AND LASER APPLICATION.” 2009. Web. 01 Mar 2021.
Vancouver:
Li D. MBE GROWTH AND CHARACTERIZATION OF Pb-SALT SEMICONDUCTORS FOR MID-INFRARED DETECTOR AND LASER APPLICATION. [Internet] [Doctoral dissertation]. University of Oklahoma; 2009. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/318915.
Council of Science Editors:
Li D. MBE GROWTH AND CHARACTERIZATION OF Pb-SALT SEMICONDUCTORS FOR MID-INFRARED DETECTOR AND LASER APPLICATION. [Doctoral Dissertation]. University of Oklahoma; 2009. Available from: http://hdl.handle.net/11244/318915
University of Oklahoma
9.
Khosravani, Shahriar.
Theoretical and experimental investigation of IV-VI mid-infrared multiple quantum wells vertical cavity surface emitting lasers.
Degree: PhD, School of Electrical and Computer Engineering, 2003, University of Oklahoma
URL: http://hdl.handle.net/11244/682
► The multilateral modes and poor heat dissipation are the main obstacles of room temperature operation. These issues were addressed by using an external cavity configuration…
(more)
▼ The multilateral modes and poor heat dissipation are the main obstacles of room temperature operation. These issues were addressed by using an external cavity configuration and by the reduction of the pump spot size to 90mum. Nevertheless, these challenges present opportunities for the ongoing research.
Advisors/Committee Members: Shi, Zhisheng, (advisor).
Subjects/Keywords: Infrared spectroscopy.; Physics, Condensed Matter.; Quantum wells.; Engineering, Electronics and Electrical.; Solid-state lasers.; Physics, Optics.
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APA (6th Edition):
Khosravani, S. (2003). Theoretical and experimental investigation of IV-VI mid-infrared multiple quantum wells vertical cavity surface emitting lasers. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/682
Chicago Manual of Style (16th Edition):
Khosravani, Shahriar. “Theoretical and experimental investigation of IV-VI mid-infrared multiple quantum wells vertical cavity surface emitting lasers.” 2003. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/682.
MLA Handbook (7th Edition):
Khosravani, Shahriar. “Theoretical and experimental investigation of IV-VI mid-infrared multiple quantum wells vertical cavity surface emitting lasers.” 2003. Web. 01 Mar 2021.
Vancouver:
Khosravani S. Theoretical and experimental investigation of IV-VI mid-infrared multiple quantum wells vertical cavity surface emitting lasers. [Internet] [Doctoral dissertation]. University of Oklahoma; 2003. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/682.
Council of Science Editors:
Khosravani S. Theoretical and experimental investigation of IV-VI mid-infrared multiple quantum wells vertical cavity surface emitting lasers. [Doctoral Dissertation]. University of Oklahoma; 2003. Available from: http://hdl.handle.net/11244/682
University of Oklahoma
10.
Ray, Dewali.
Development of lead-chalcogenide mid-infrared light emitting devices.
Degree: PhD, School of Electrical and Computer Engineering, 2007, University of Oklahoma
URL: http://hdl.handle.net/11244/1149
► The research described by this dissertation has focused on the fabrication and design, for the improvement of lead chalcogenide lasers. The ultimate goal was to…
(more)
▼ The research described by this dissertation has focused on the fabrication and design, for the improvement of lead chalcogenide lasers. The ultimate goal was to develop TE-cooled single-mode continuous wave Mid-IR laser for high resolution spectroscopic applications. Processing techniques and procedures as well as theoretical design have been successfully developed that could lead to high temperature single-mode continuous wave (CW) laser operation. Light emitting Pb-salt structures on BaF2 substrate has been examined. An antireflection coating material, for diode-pumped Pb-salt light emitters, that has enhanced room temperature continuous wave light emission has been described. A new surface preparation technology for epi-ready [110] oriented BaF2 substrates and a novel mounting technique for the fabrication of cleaved cavity Pb-salt laser grown on {110} BaF2 was developed. Lasing results from [110] oriented Pb-salt laser fabricated on PbSnSe substrate have been reported for the first time. Theoretical modeling of a Pb-Salt ridge waveguide laser for single lateral mode operation and the development of a fabrication process for the same has been described. A novel fabrication method of cleaved facet Pb-salt laser on as-grown metal substrate for high temperature operation of the device has been described.
Advisors/Committee Members: Shi, Zhisheng, (advisor).
Subjects/Keywords: Molecular spectroscopy.; Lead chalcogenides.; Lasers.; Engineering, Electronics and Electrical.
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APA ·
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MLA ·
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CSE |
Export
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Manager
APA (6th Edition):
Ray, D. (2007). Development of lead-chalcogenide mid-infrared light emitting devices. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/1149
Chicago Manual of Style (16th Edition):
Ray, Dewali. “Development of lead-chalcogenide mid-infrared light emitting devices.” 2007. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/1149.
MLA Handbook (7th Edition):
Ray, Dewali. “Development of lead-chalcogenide mid-infrared light emitting devices.” 2007. Web. 01 Mar 2021.
Vancouver:
Ray D. Development of lead-chalcogenide mid-infrared light emitting devices. [Internet] [Doctoral dissertation]. University of Oklahoma; 2007. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/1149.
Council of Science Editors:
Ray D. Development of lead-chalcogenide mid-infrared light emitting devices. [Doctoral Dissertation]. University of Oklahoma; 2007. Available from: http://hdl.handle.net/11244/1149
University of Oklahoma
11.
Mukherjee, Shaibal.
IV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATIONIV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATION.
Degree: PhD, 2009, University of Oklahoma
URL: http://hdl.handle.net/11244/318958
► A study on the measurement of minority carrier lifetime, which is one of the very important figures of merit to judge opto-electronic device performance, is…
(more)
▼ A study on the measurement of minority carrier lifetime, which is one of the very important figures of merit to judge opto-electronic device performance, is illustrated. Photoconductive decay (PCD) method, a very popular and well-established methodology has been adopted to carry out the experimental work. The implementation of CaF2 as a new surface passivation layer for MBE-grown PbSe single crystalline thin films on a BaF2(111) substrate has been done and the corresponding effect on device performance is compared. Minority carrier lifetimes and pulsed photoluminescence intensities from PbSe samples are observed to increase after CaF2 surface passivation. However, the improvement is comparatively more significant at low temperature than at high temperature. This may indicate that surface passivation for Pb-salt materials are not as critical as its II-VI and III-V counterparts at high temperature of device operation. Therefore, device fabrication for Pb-salt materials at elevated temperature could be relatively more cost-effective with a higher-yield.
Advisors/Committee Members: Shi, Zhisheng (advisor).
Subjects/Keywords: Solid-state lasers; Quantum wells; Semiconductors
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APA (6th Edition):
Mukherjee, S. (2009). IV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATIONIV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATION. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/318958
Chicago Manual of Style (16th Edition):
Mukherjee, Shaibal. “IV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATIONIV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATION.” 2009. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/318958.
MLA Handbook (7th Edition):
Mukherjee, Shaibal. “IV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATIONIV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATION.” 2009. Web. 01 Mar 2021.
Vancouver:
Mukherjee S. IV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATIONIV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATION. [Internet] [Doctoral dissertation]. University of Oklahoma; 2009. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/318958.
Council of Science Editors:
Mukherjee S. IV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATIONIV-VI LEAD SALT MID-INFRARED LIGHT EMITTING DEVICE DESIGN, FABRICATION AND CHARACTERIZATION. [Doctoral Dissertation]. University of Oklahoma; 2009. Available from: http://hdl.handle.net/11244/318958
12.
Ye, Hao.
Molecular Beam Epitaxy of InAs, GaSb, AlSb Structures for Interband Cascade Devices.
Degree: PhD, 2016, University of Oklahoma
URL: http://hdl.handle.net/11244/34898
► The interband cascade (IC) family of devices has been extended beyond mid-infrared lasers to include photovoltaic (PV) and photodetector (PD) devices. These devices utilize the…
(more)
▼ The interband cascade (IC) family of devices has been extended beyond mid-infrared lasers to include photovoltaic (PV) and photodetector (PD) devices. These devices utilize the transition between conduction and valence bands for photon emission or absorption in the infrared region. The cascade structure recycles electrons to generate or collect multiple photons per electron. Epitaxial growths of the device structures are challenging because they consist of hundreds of quantum wells and require atomic layer precision in thickness control. Molecular beam epitaxy (MBE) was used to grow these structures with InAs, GaSb, AlSb, and their alloys on InAs or GaSb substrates.
IC laser structures with InAs plasmon cladding layers were grown on InAs substrates for wavelengths greater than 3 μm. To provide a smooth initial surface for the cascade region, the optimal conditions for growth of homoepitaxial InAs layers were investigated over a wide range of substrate temperatures and As2/In flux ratios at a growth rate of 0.66 monolayer/s (ML/s). Material quality was investigated using differential interference contrast microscopy, scanning electron microscopy, and atomic force microscopy. The geometry of oval hillock defects on the InAs layers suggested that these defects originated at the substrate surface. The InAs-based IC lasers had emission wavelengths out to 11 μm, which is the longest wavelength among interband lasers based on III–V materials. By introducing intermediate superlattice (SL) cladding layers to enhance optical confinement and reduce internal absorption loss, the first continuous wave operation of InAs-based IC lasers at room temperature was demonstrated. The threshold current density of 247 A/cm2 for emission near 4.6 μm is the lowest ever reported among semiconductor mid-infrared lasers at similar wavelengths.
ICPV and ICPD devices were developed based on the architecture of IC lasers. They both consist of multiple discrete InAs/GaSb SL absorbers sandwiched between electron and hole barriers. ICPV devices can be used in thermophotovoltaic systems that convert radiant energy from a heat source into electricity. Strain-balanced InAs/GaSb SL structures were achieved by adjusting the group-V overpressure during MBE growth. Two- and three-stage ICPV devices operated at room temperature with substantial open-circuit voltages at a cutoff wavelength of 5.3 μm, the longest ever reported for room-temperature PV devices.
The interfaces of InAs/GaSb SLs were studied with the goal of improving the PDs designed for the long-wavelength infrared region. Two ICPD structures with different SL interfaces were grown by MBE, one with a ~1.2 ML-thick InSb layer inserted intentionally only at the GaSb-on-InAs interfaces and another with a ~0.6 ML-thick InSb layer inserted at both InAs-on-GaSb and GaSb-on-InAs interfaces. The material quality of the PD structures was similar according to differential interference contrast microscopy, atomic force microscopy, and x-ray diffraction measurements. The device performances were not…
Advisors/Committee Members: Yang, Rui (advisor), Santos, Michael (advisor), Murphy, Sheena (committee member), Ruyle, Jessica (committee member), Shi, Zhisheng (committee member), Johnson, Matthew (committee member).
Subjects/Keywords: Molecular Beam Epitaxy; III-V Semiconductor Material; Laser; Detector
…at the University of
Oklahoma [24]. There are several advantages of using the…
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Ye, H. (2016). Molecular Beam Epitaxy of InAs, GaSb, AlSb Structures for Interband Cascade Devices. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/34898
Chicago Manual of Style (16th Edition):
Ye, Hao. “Molecular Beam Epitaxy of InAs, GaSb, AlSb Structures for Interband Cascade Devices.” 2016. Doctoral Dissertation, University of Oklahoma. Accessed March 01, 2021.
http://hdl.handle.net/11244/34898.
MLA Handbook (7th Edition):
Ye, Hao. “Molecular Beam Epitaxy of InAs, GaSb, AlSb Structures for Interband Cascade Devices.” 2016. Web. 01 Mar 2021.
Vancouver:
Ye H. Molecular Beam Epitaxy of InAs, GaSb, AlSb Structures for Interband Cascade Devices. [Internet] [Doctoral dissertation]. University of Oklahoma; 2016. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11244/34898.
Council of Science Editors:
Ye H. Molecular Beam Epitaxy of InAs, GaSb, AlSb Structures for Interband Cascade Devices. [Doctoral Dissertation]. University of Oklahoma; 2016. Available from: http://hdl.handle.net/11244/34898
. 
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