+publisher:"Brown University" +contributor:("Paine, David")

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1. Jiang, Wenyan. Processing and Thermoelectric Properties of Thick Film Based Oxide Composite Materials.

Degree: PhD, Materials Science, 2015, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:419407/

► Oxide materials have been a focus of recent thermoelectric research due to their thermal and chemical stability as well as cost effectiveness. In this thesis… (more)

▼ Oxide materials have been a focus of recent thermoelectric research due to their thermal and chemical stability as well as cost effectiveness. In this thesis work, LaCoO3 based oxides are studied in order to improve the thermoelectric performance while keeping the processing and materials costs low. In order to understand the importance of the material thickness scaling effect, an analytical device modeling work is performed. The modeling results indicate the film thickness for optimum device performance is in the range 100µm -300µm. For this thickness range, an innovative low cost hybrid processing method is developed, which integrates some well-known processing steps, including screen printing and spin coating. The porous thick film body is prepared using screen printing, and a solution is infiltrated into the thick film by spin coating. In addition to the advantage of cost efficiency, the method presents unique opportunities to investigate thermoelectric property improvement using oxide composite materials. Facilitated by this method, two types of composite materials are prepared. By using the solution that has the same composition as the screen printed film, LaNi0.1Co0.9O3 samples with different porosity are prepared by changing the amount of solution infiltrated into the film. The infiltration results in relatively wide pore size distribution. For this pore size range, the Seebeck coefficient is porosity independent. The contradiction between this experimental result and the previous theoretical prediction is discussed. The trade-off between the thermal and electrical conductivity indicates that the porosity has a minor impact on the thermoelectric figure of merit ZT. In contrast, by changing the composition of the infiltration solution, a second type of composite film, a multiphase film is prepared with a core-shell structure. Composite film formed by core material LaNi0.1Co0.9O3 and shell material La0.9Sr0.1Ni0.2Co0.8O3 shows 60% ZT improvement compared with the single phase porous samples. Successful decoupling between thermal conductivity and electrical conductivity is therefore demonstrated using this unique processing method. Advisors/Committee Members: Kingon, Angus (Director), Paine, David (Reader), Sheldon, Brian (Reader).

Subjects/Keywords: Oxide Thermoelectric

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APA (6^th Edition):

Jiang, W. (2015). Processing and Thermoelectric Properties of Thick Film Based Oxide Composite Materials. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:419407/

Chicago Manual of Style (16^th Edition):

Jiang, Wenyan. “Processing and Thermoelectric Properties of Thick Film Based Oxide Composite Materials.” 2015. Doctoral Dissertation, Brown University. Accessed January 20, 2021. https://repository.library.brown.edu/studio/item/bdr:419407/.

MLA Handbook (7^th Edition):

Jiang, Wenyan. “Processing and Thermoelectric Properties of Thick Film Based Oxide Composite Materials.” 2015. Web. 20 Jan 2021.

Vancouver:

Jiang W. Processing and Thermoelectric Properties of Thick Film Based Oxide Composite Materials. [Internet] [Doctoral dissertation]. Brown University; 2015. [cited 2021 Jan 20]. Available from: https://repository.library.brown.edu/studio/item/bdr:419407/.

Council of Science Editors:

Jiang W. Processing and Thermoelectric Properties of Thick Film Based Oxide Composite Materials. [Doctoral Dissertation]. Brown University; 2015. Available from: https://repository.library.brown.edu/studio/item/bdr:419407/

2. Lee, Sunghwan. Amorphous IZO-based Thin Film Transistors: Native Defect-based Doping, Amorphous Phase Instabilities, Threshold Voltage Shifts, and Metallization Strategies.

Degree: PhD, Materials Science, 2013, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:320542/

► Amorphous oxide semiconductor (AOS) thin film transistors (TFTs) based on In2O3 have attracted much interest for use as pixel switching elements in next generation active-matrix… (more)

▼ Amorphous oxide semiconductor (AOS) thin film transistors (TFTs) based on In2O3 have attracted much interest for use as pixel switching elements in next generation active-matrix liquid crystal (AM-LCD) and active-matrix organic light emitting diode (AM-OLED) displays. The high field effect mobility of In2O3-based AOS devices (10–25 cm2/Vsec) offers significant performance improvements over present-day a-Si TFTs (<1 cm2/Vsec) technology. Additional advantages of AOS materials include low temperature processing (RT–300 °C), isotropic wet etch characteristics, and high optical transparency (<85 % in the visible regime) all of which make this material suitable for large area, flexible, and transparent devices on inexpensive polymer substrates. We have investigated the electrical and structural stability of a-IZO TFTs. Pure amorphous In2O3 is unstable and crystallizes to the bixbyite phase at <150 °C. However, the amorphous phase can be stabilized to temperatures up to 600 °C by the addition of 10 wt% ZnO (a-IZO). We reported high performance long-channel a-IZO n–MOSFETs which operate in depletion-mode (VTh~ –3.21 V) and have saturation field effect mobility of (μsat) of ~>18 cm2/Vsec and on/off ratio of >106. These demonstration devices were fabricated on thermally oxidized Si that used the Si as a bottom-gate, thermal SiO2 as the gate dielectric, semiconducting a-IZO as the channel and conducting a-IZO as the source/drain metallization. We have also deposited TFTs with sputtered dielectric layers to demonstrate an all-room temperature TFT fabrication process. Challenges for the implementation of a-IZO as a TFT channel material which include dominant doping mechanism, contact properties, and their effect on the field effect mobility measurements, metallization-induced amorphous phase and threshold voltage instability, and metallization strategies were investigated. Research findings in this thesis may be significant to some amorphous IZO and IGZO TFTs to understand fundamental characteristics of materials and devices for the potential use of ultra high definition display device applications such as active-matrix organic light-emitting diodes (AMOLED). Advisors/Committee Members: Paine, David (Director), Zaslavsky, Alexander (Reader), Chason, Eric (Reader).

Subjects/Keywords: Amorphous oxide semiconductors

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APA (6^th Edition):

Lee, S. (2013). Amorphous IZO-based Thin Film Transistors: Native Defect-based Doping, Amorphous Phase Instabilities, Threshold Voltage Shifts, and Metallization Strategies. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320542/

Chicago Manual of Style (16^th Edition):

Lee, Sunghwan. “Amorphous IZO-based Thin Film Transistors: Native Defect-based Doping, Amorphous Phase Instabilities, Threshold Voltage Shifts, and Metallization Strategies.” 2013. Doctoral Dissertation, Brown University. Accessed January 20, 2021. https://repository.library.brown.edu/studio/item/bdr:320542/.

MLA Handbook (7^th Edition):

Vancouver:

Lee S. Amorphous IZO-based Thin Film Transistors: Native Defect-based Doping, Amorphous Phase Instabilities, Threshold Voltage Shifts, and Metallization Strategies. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2021 Jan 20]. Available from: https://repository.library.brown.edu/studio/item/bdr:320542/.

Council of Science Editors:

Lee S. Amorphous IZO-based Thin Film Transistors: Native Defect-based Doping, Amorphous Phase Instabilities, Threshold Voltage Shifts, and Metallization Strategies. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320542/

3. Ishii, Yohei. Self-organized ripple formation during ion bombardment: Relation to stress, viscous flow and defect kinetics.

Degree: PhD, Materials Science, 2013, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:320547/

► Self-organized pattern formation can be produced by low energy ion bombardment. A continuum theory explains the ion-induced surface morphology evolution in terms of a balance… (more)

▼ Self-organized pattern formation can be produced by low energy ion bombardment. A continuum theory explains the ion-induced surface morphology evolution in terms of a balance between roughening (by sputtering) and smoothing (by surface transport). Although this approach accounts for many experimental features, it does not provide good quantitative agreement with observed ripple formation kinetics and structure. Additional physical mechanisms such as the effect of ion-induced stress, ion-enhanced viscous flow, mass redistribution due to ion impact and Ehrlich-Schwoebel barriers to interlayer diffusion have been proposed to extend the original model. To explore the effect of ion-induced stress, we studied stress evolution in silicon during ion bombardment and relaxation after the ion bombardment was stopped. We developed a model to explain the stress evolution and relaxation behavior in terms of stress generation by ion implantation and relaxation by ion-enhanced viscous flow. By comparing the model with experimental results, we determined that a bimolecular annihilation process (annihilation of dangling bonds) is the dominant process controlling the concentration of flow defects during and after ion bombardment. This analysis also enabled us to directly determine the dependence of the inverse viscosity on the defect concentration. We applied this model to the ripple formation theory to show that stress is not playing a significant role in enhancing ripple growth in amorphous Si. We also used a Kinetic Monte Carlo simulation of self-organized ripple formation during sputtering. We incorporated multiple defect production by each ion impingement and an Ehrlich-Schwoebel (ES) barrier into the simulation. The results show that these effects change the ion-induced surface evolution but not enough to explain the discrepancy between the model and experiments. Therefore, in this dissertation, we showed both theoretical and experimental approaches to understanding self-organized ripple formation during ion bombardment. Advisors/Committee Members: Chason, Eric (Director), Paine, David (Reader), Kim, Kyung-Suk (Reader).

Subjects/Keywords: self-organized

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ishii, Y. (2013). Self-organized ripple formation during ion bombardment: Relation to stress, viscous flow and defect kinetics. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320547/

Chicago Manual of Style (16^th Edition):

Ishii, Yohei. “Self-organized ripple formation during ion bombardment: Relation to stress, viscous flow and defect kinetics.” 2013. Doctoral Dissertation, Brown University. Accessed January 20, 2021. https://repository.library.brown.edu/studio/item/bdr:320547/.

MLA Handbook (7^th Edition):

Ishii, Yohei. “Self-organized ripple formation during ion bombardment: Relation to stress, viscous flow and defect kinetics.” 2013. Web. 20 Jan 2021.

Vancouver:

Ishii Y. Self-organized ripple formation during ion bombardment: Relation to stress, viscous flow and defect kinetics. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2021 Jan 20]. Available from: https://repository.library.brown.edu/studio/item/bdr:320547/.

Council of Science Editors:

Ishii Y. Self-organized ripple formation during ion bombardment: Relation to stress, viscous flow and defect kinetics. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320547/

4. Song, Yang. Characteristics and Stability of High Performance Indium Zinc Oxide Thin Film Transistors.

Degree: Department of Physics, 2018, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:792638/

► Amorphous oxide semiconductors (AOSs) have been intensively studied during the last 15 years due to their superior properties. The major application of AOS thin film… (more)

▼ Amorphous oxide semiconductors (AOSs) have been intensively studied during the last 15 years due to their superior properties. The major application of AOS thin film transistors (TFTs) is displays. Compared to the previous generation TFT material—amorphous silicon (a-Si)—AOSs have higher mobility, and can be easily deposited by various deposition techniques at room temperature on arbitrary substrates. This thesis focuses on the characteristics and stability of a specific AOS, amorphous indium zinc oxide (a-IZO), as an electronic material for TFTs. We have fabricated a-IZO TFTs with a top-gate structure by using the in-situ gate dielectric formation technique: some metals—such as Al and Hf—can react with IZO to form an oxide insulator layer in the absence of kinetic constraints. The in-situ dielectric formation can provide a high-quality insulator/IZO interface with a low interface trap density, leading to excellent TFT performance. The subthreshold slope in our best IZO TFTs reaches a value of 62 mV/decade, close to the room temperature theoretical limit, and our devices also show on/off current ratios above 10⁷ and a high extracted field effect mobility around 100 cm2/V·s. These are state-of-the-art results in AOS TFTs. Another focus in our work is the stability of IZO TFTs, where oxygen vacancy generation and migration are used to explain the observed experimental threshold voltage shifts in a-IZO TFTs as a function of aging and applied gate bias. As a possible future research direction, the high electron mobility and controllable high electron density make a-IZO a promising candidate for high-speed, high-power radio frequency transistors. We propose a vertical transistor structure with buried multi-gate fingers. Unlike in the previously studied single-crystal nanowire or permeable base vertical transistors, the properties of a-IZO make it possible to regrow the vertical semiconductor channels without any high temperature epitaxy, lowering fabrication complexity and cost while making the vertical IZO device compatible with arbitrary substrates. Preliminary fabrication process and characterization results of the vertical-current-flow a-IZO TFT are shown and discussed. Advisors/Committee Members: Zaslavsky, Alexander (Advisor), Paine, David (Advisor), Valles, James (Reader), Mitrovic, Vesna (Reader).

Subjects/Keywords: Indium zinc oxide

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Song, Y. (2018). Characteristics and Stability of High Performance Indium Zinc Oxide Thin Film Transistors. (Thesis). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:792638/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Song, Yang. “Characteristics and Stability of High Performance Indium Zinc Oxide Thin Film Transistors.” 2018. Thesis, Brown University. Accessed January 20, 2021. https://repository.library.brown.edu/studio/item/bdr:792638/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Song, Yang. “Characteristics and Stability of High Performance Indium Zinc Oxide Thin Film Transistors.” 2018. Web. 20 Jan 2021.

Vancouver:

Song Y. Characteristics and Stability of High Performance Indium Zinc Oxide Thin Film Transistors. [Internet] [Thesis]. Brown University; 2018. [cited 2021 Jan 20]. Available from: https://repository.library.brown.edu/studio/item/bdr:792638/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Song Y. Characteristics and Stability of High Performance Indium Zinc Oxide Thin Film Transistors. [Thesis]. Brown University; 2018. Available from: https://repository.library.brown.edu/studio/item/bdr:792638/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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