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Influence Of Al2o3 Passivation Layer Thickness On The Thermal Stability And Quality Of Mocvd-Grown Gan On Si, S M Atiqur Rahman, Manika Tun Nafisa, Zhe Chuan Feng, Benjamin Klein, Ian T. Ferguson 2024 Kennesaw State University

Influence Of Al2o3 Passivation Layer Thickness On The Thermal Stability And Quality Of Mocvd-Grown Gan On Si, S M Atiqur Rahman, Manika Tun Nafisa, Zhe Chuan Feng, Benjamin Klein, Ian T. Ferguson

Symposium of Student Scholars

This research delves into the significant impact of varying thicknesses of the Al2O3 passivation layer on the thermal stability and crystalline quality of GaN on Si structures, an essential aspect for the next generation of high-temperature electronic and optoelectronic devices. By adopting metal-organic chemical vapor deposition (MOCVD) for the growth process, we analyzed structures with different Al2O3 passivation layer thicknesses: none, 2 nm, 10 nm, and 20 nm, each built upon the GaN layer. Through Raman spectroscopy, we meticulously assessed the changes in the E2 (High) phonon mode's peak position and full width …


Reducing Switching Noise And Losses In Two-Stage Electric Power Converters, Abhijeet Prem 2024 Portland State University

Reducing Switching Noise And Losses In Two-Stage Electric Power Converters, Abhijeet Prem

Student Research Symposium

Advancements in semiconductor devices are enabling the design of better electrical power converter systems. Wide Bandgap (WBG) switching devices from Silicon Carbide and Gallium Nitride can operate at high temperatures, voltages, and frequencies with faster turn-on/off periods, improving converter performance over silicon devices. However, WBG technology is still new, and the rapid switching transitions of these devices lead to issues such as voltage overshoots, ringing, and electromagnetic interference, which need to be addressed for widespread adoption. This work introduces a new control method for reshaping the switching voltages, which overcomes the disadvantages of fast transition time without increasing the system's …


Fabrication Of Two-Dimensional Material-Based Nano-Capacitors Using Bismuth Selenite (Bi2seo5) To Study Its Dielectric Properties, Major KC 2024 Washington University in St. Louis

Fabrication Of Two-Dimensional Material-Based Nano-Capacitors Using Bismuth Selenite (Bi2seo5) To Study Its Dielectric Properties, Major Kc

McKelvey School of Engineering Theses & Dissertations

In recent years, the demand for high-performance micro and nanodevices has surged, necessitating the exploration of novel dielectric materials to replace conventional silicon dioxide. Following the continuation of the Moorse law, as device dimensions reduce to nanoscale levels, the properties of silicon dioxide can degrade, leading to issues such as increased leakage current and reduced gate control. Materials with superior electrical properties, such as higher dielectric constant, lower leakage current, and better thermal stability allowing for the development of faster, more efficient, and more reliable devices are in higher demand than ever. Two-dimensional layered semiconductor nanomaterials represented by compounds such …


The Analysis Of Mechanical Exfoliation Of Graphene For Various Fabrication And Automation Techniques, Lance Yarbrough 2024 University of Arkansas, Fayetteville

The Analysis Of Mechanical Exfoliation Of Graphene For Various Fabrication And Automation Techniques, Lance Yarbrough

Mechanical Engineering Undergraduate Honors Theses

Mechanical Exfoliation of Graphene is an often-overlooked portion of the fabrication of quantum devices, and to create more devices quickly, optimizing this process to generate better flakes is critical. In addition, it would be valuable to simulate test pulls quickly, to gain insight on flake quality of various materials and exfoliation conditions. Physical pulls of graphene at various temperatures, pull forces, and pull repetitions were analyzed and compared to the results of ANSYS simulations, solved for similar results. Using ANSYS’ ability to predict trends in exfoliations, flake thickness and coverage using stress and deflection analyses were investigated. Generally, both strongly …


The Analysis Of Mechanical Exfoliation Of Graphene For Various Fabrication And Automation Techniques, Lance Yarbrough 2024 University of Arkansas, Fayetteville

The Analysis Of Mechanical Exfoliation Of Graphene For Various Fabrication And Automation Techniques, Lance Yarbrough

Physics Undergraduate Honors Theses

Mechanical Exfoliation


Encapsulated 2d Materials And The Potential For 1d Electrical Contacts, Sarah Wittenburg 2024 University of Arkansas, Fayetteville

Encapsulated 2d Materials And The Potential For 1d Electrical Contacts, Sarah Wittenburg

Physics Undergraduate Honors Theses

The utilization of two-dimensional materials and heterostructures, particularly graphene and hexagonal boron nitride, have garnered significant attention in the realm of nanoelectronics due to their unique properties and versatile functionalities. This study focuses on the synthesis and fabrication processes of monolayer graphene encapsulated between layers of hBN, aiming to explore the potential of these heterostructures for various electronic applications. The encapsulation of graphene within hBN layers not only enhances device performance but also shields graphene from environmental contaminants, ensuring long-term stability. Experimental techniques, including mechanical exfoliation and stamp-assisted transfer, are employed to construct three-layer stacks comprising hBN-graphene-hBN. The fabrication process …


A Comprehensive Materials Approach To Thermal Management In Fiber Lasers, Bailey Meehan 2024 Clemson University

A Comprehensive Materials Approach To Thermal Management In Fiber Lasers, Bailey Meehan

All Dissertations

Optical fiber-based amplifiers and lasers enable a great many useful devices and conveniences. Unfortunately, however, they can generate considerable heat during operation that drives the need for complex cooling solutions, thus reducing many of the size, weight, and power (SWAP) benefits for which fiber lasers are known. Additionally, at elevated temperatures, thermally-driven phenomena, such as Transverse Mode Instability (TMI), can be induced that limit the power-scaling of fiber lasers. The focus of this Dissertation is to explore novel approaches to thermal management in fiber lasers through judicious materials science and engineering to obviate the aforementioned limitations. Fibers studied in this …


Volatile Crystalline Semiconductor Core Fibers, Thomasina Zaengle 2024 Clemson University

Volatile Crystalline Semiconductor Core Fibers, Thomasina Zaengle

All Dissertations

Optical fibers play critical roles across many facets of everyday life from communications to e-commerce to sensing and security. The ubiquity of optical fibers arises from their intrinsic clarity and, as glasses, their ability to be thermally drawn at high speeds over long distances when suitably heated about their glass transition temperature. Sixteen years ago, the first thermally drawn crystalline core fibers were fabricated using the molten core method, whereby a melt is confined within a glass capillary tube that is then drawn to fiber. This opened the door to crystalline semiconductor core fibers, which are now the backbone of …


Development Of Novel Cesium Chloride-Based Ultrafast Inorganic Scintillators For Fast Timing Radiation Detection Applications, Daniel Rutstrom 2024 University of Tennessee, Knoxville

Development Of Novel Cesium Chloride-Based Ultrafast Inorganic Scintillators For Fast Timing Radiation Detection Applications, Daniel Rutstrom

Doctoral Dissertations

Cs2ZnCl4 [dicesium zinc tetrachloride] and Cs3ZnCl5 [tricesium zinc pentachloride] are relatively new scintillator materials that appear to be promising for use in fast-timing radiation detection applications owing to their 1 to 2 nanosecond decay times. Moreover, they offer several advantages over the state-of-the-art ultrafast inorganic scintillator BaF2 [barium fluoride]. To fully realize the potential of these novel materials, growth of crystals having improved optical quality must be demonstrated. The mechanism responsible for the ultrafast decay times, core valence luminescence (CVL), in cesium zinc chloride crystals can also be observed in other compounds containing …


Deep Selenium Donors In Zngep2 Crystals: An Electron Paramagnetic Resonance Study Of A Nonlinear Optical Material, Timothy D. Gustafson, Larry E. Halliburton, Nancy C. Giles, Peter G. Schunemann, Kevin T. Zawilski, J. Jesenovec, Kent L. Averett, Jeremy Slagle 2024 Air Force Institute of Technology

Deep Selenium Donors In Zngep2 Crystals: An Electron Paramagnetic Resonance Study Of A Nonlinear Optical Material, Timothy D. Gustafson, Larry E. Halliburton, Nancy C. Giles, Peter G. Schunemann, Kevin T. Zawilski, J. Jesenovec, Kent L. Averett, Jeremy Slagle

Faculty Publications

Zinc germanium diphosphide (ZnGeP2) is a ternary semiconductor best known for its nonlinear optical properties. A primary application is optical parametric oscillators operating in the mid-infrared region. Controlled donor doping provides a method to minimize the acceptor-related absorption bands that limit the output power of these devices. In the present study, a ZnGeP2 crystal is doped with selenium during growth. Selenium substitutes for phosphorus and serves as a deep donor. Significant concentrations of native defects (zinc vacancies, germanium-on-zinc antisites, and phosphorous vacancies) are also present in the crystal. Electron paramagnetic resonance (EPR) is used to establish the …


Research On 3d Printing Resin Exposure Properties And Its Application On Centrifugal Microfluidic Platform Based On Fluorescence Detection, Zheng Qiao 2024 Louisiana State University and Agricultural and Mechanical College

Research On 3d Printing Resin Exposure Properties And Its Application On Centrifugal Microfluidic Platform Based On Fluorescence Detection, Zheng Qiao

LSU Doctoral Dissertations

This dissertation encapsulates significant advancements in the field of SLA 3D printing and centrifugal microfluidics. Central to the research is the development of a novel mathematical model for predicting trapped resin thickness in SLA 3D printing, a groundbreaking contribution that addresses a critical aspect of printing intricate structures. This model, the first to establish a mathematical relationship for resin thickness, is rooted in a comprehensive study of the resin curing process. The research leverages the concept of 'critical dosage' for resin curing, leading to a more refined and theoretically grounded approach for calculating curing thickness. Experimentation further validates the model, …


Effect Of Fabrication Parameters On The Ferroelectricity Of Hafnium Zirconium Oxide Films: A Statistical Study, Guillermo A. Salcedo, Ahmad E. Islam, Elizabeth Reichley, Michael Dietz, Christine M. Schubert Kabban, Kevin D. Leedy, Tyson C. Back, Weison Wang, Andrew Green, Timothy S. Wolfe, James M. Sattler 2024 Air Force Institute of Technology

Effect Of Fabrication Parameters On The Ferroelectricity Of Hafnium Zirconium Oxide Films: A Statistical Study, Guillermo A. Salcedo, Ahmad E. Islam, Elizabeth Reichley, Michael Dietz, Christine M. Schubert Kabban, Kevin D. Leedy, Tyson C. Back, Weison Wang, Andrew Green, Timothy S. Wolfe, James M. Sattler

Faculty Publications

Ferroelectricity in hafnium zirconium oxide (Hf1−xZrxO2) and the factors that impact it have been a popular research topic since its discovery in 2011. Although the general trends are known, the interactions between fabrication parameters and their effect on the ferroelectricity of Hf1−xZrxO2 require further investigation. In this paper, we present a statistical study and a model that relates Zr concentration (x), film thickness (tf), and annealing temperature (Ta) with the remanent polarization (Pr) in tungsten (W)-capped Hf1−xZrxO2. …


Micropatterning And Functionalization Of Single Layer Graphene: Tuning Its Electron Transport Properties, Miao-Miao Cui, Lian-Huan Han, Lan-Ping Zeng, Jia-Yao Guo, Wei-Ying Song, Chuan Liu, Yuan-Fei Wu, Shi-Yi Luo, Yun-Hua Liu, Dong-Ping Zhan 2024 Department of Chemistry, College of Chemistry and Chemical Engineering; State Key Laboratory of Physical Chemistry of Solid Surfaces (PCOSS); Engineering Research Center of Electrochemical Technologies of Ministry of Education; Xiamen University; Xiamen 361005, China

Micropatterning And Functionalization Of Single Layer Graphene: Tuning Its Electron Transport Properties, Miao-Miao Cui, Lian-Huan Han, Lan-Ping Zeng, Jia-Yao Guo, Wei-Ying Song, Chuan Liu, Yuan-Fei Wu, Shi-Yi Luo, Yun-Hua Liu, Dong-Ping Zhan

Journal of Electrochemistry

As a promising 2D material, graphene exhibits excellent physical properties including single-atom-scale thickness and remarkably high charge carrier mobility. However, its semi-metallic nature with a zero bandgap poses challenges for its application in high-performance field-effect transistors (FETs). In order to overcome these limitations, various approaches have been explored to modulate graphene's bandgap, including nanoscale confinement, external field induction, doping, and chemical micropatterning. Nevertheless, the stability and controllability still need to be improved. In this study, we propose a feasible method that combines electrochemical bromination and photolithography to precisely tune the electron transport properties of single layer graphene (SLG). Through this …


Recent Advances In Solar Photo(Electro)Catalytic Nitrogen Fixation, Jun-Bo Ma, Sheng Lin, Zhiqun Lin, Lan Sun, Chang-Jian Lin 2024 State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China

Recent Advances In Solar Photo(Electro)Catalytic Nitrogen Fixation, Jun-Bo Ma, Sheng Lin, Zhiqun Lin, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Ammonia (NH3) is an essential chemical in modern society. It is currently produced in industry by the Haber-Bosch process using H2 and N2 as reactants in the presence of iron-based catalysts at high-temperature (400–600 oC) and extremely highpressure (20–40 MPa) conditions. However, its efficiency is limited to 10% to 15%. At the same time, a large amount of energy is consumed, and CO2 emission is inevitably. The development of a sustainable, clean, and environmentally friendly energy system represents a key strategy to address energy crisis and environmental pollution, ultimately aiming to achieve carbon neutrality. …


Machine Learning Prediction Of Photoluminescence In Mos2: Challenges In Data Acquisition And A Solution Via Improved Crystal Synthesis, Ethan Swonger, John Mann, Jared Horstmann, Daniel Yang 2024 Pepperdine University

Machine Learning Prediction Of Photoluminescence In Mos2: Challenges In Data Acquisition And A Solution Via Improved Crystal Synthesis, Ethan Swonger, John Mann, Jared Horstmann, Daniel Yang

Seaver College Research And Scholarly Achievement Symposium

Transition metal dichalcogenides (TMDCs) like molybdenum disulfide (MoS2) possess unique electronic and optical properties, making them promising materials for nanotechnology. Photoluminescence (PL) is a key indicator of MoS2 crystal quality. This study aimed to develop a machine-learning model capable of predicting the peak PL wavelength of single MoS2 crystals based on micrograph analysis. Our limited ability to consistently synthesize high-quality MoS2 crystals hampered our ability to create a large set of training data. The project focus shifted towards improving MoS2 crystal synthesis to generate improved training data. We implemented a novel approach utilizing low-pressure chemical vapor deposition (LPCVD) combined with …


Raman Spectroscopy Of Gan On Si With Varied Thin Film Thickness For High-Temperature Semiconductor Devices, Manika Tun Nafisa 2024 Kennesaw State University

Raman Spectroscopy Of Gan On Si With Varied Thin Film Thickness For High-Temperature Semiconductor Devices, Manika Tun Nafisa

Symposium of Student Scholars

This study explores the potential of GaN on Si thin films as a promising material for high-temperature semiconductor devices, owing to its impressive thermal properties and performance characteristics. Two GaN on Si samples were grown using Metal Organic Chemical Vapor Deposition (MOCVD), with different film thicknesses, and their potential for high-temperature applications was comprehensively assessed by performing Raman spectroscopy at various temperature levels. The experimental results provided valuable insights into the material's behavior at elevated temperatures. At 300°C, the GaN E2 (High) peak showed a Raman shift at 562.38 cm⁻¹ for high-thickness samples and 561.49 cm⁻¹ for low-thickness samples. …


Thermal, Electrical, And Spin Transport: Encompassing Low-Damping Ferromagnets And Antiferromagnetic/Ferromagnetic Heterostructures, Matthew Ryan Natale 2024 University of Denver

Thermal, Electrical, And Spin Transport: Encompassing Low-Damping Ferromagnets And Antiferromagnetic/Ferromagnetic Heterostructures, Matthew Ryan Natale

Electronic Theses and Dissertations

Continuing technological advancements bring forth escalating challenges in global energy consumption and subsequent power dissipation, posing significant economic and environmental concerns. In response to these difficulties, the fields of thermoelectrics, spintronics, and spincaloritronics emerge as contemporary solutions, each presenting unique advantages. Thermoelectric devices, based on the Seebeck effect, other a passive, carbon-free energy generating solution from waste heat. Although current thermoelectric technology encounters hurdles in achieving optimal efficiencies without intricate designs or complex materials engineering, recently research into low-damping metallic ferromagnetic thin films have provided a new method to enhance spin wave lifetimes, thus contributing to thermoelectric voltage improvements. As …


Residual Optical Absorption From Native Defects In Cdsip2 Crystals, Timothy D. Gustafson, Nancy C. Giles, Elizabeth M. Scherrer, Kevin T. Zawilski, Peter G. Schunemann, Kent L. Averett, Jonathan E. Slagle, Larry E. Halliburton 2024 Air Force Institute of Technology

Residual Optical Absorption From Native Defects In Cdsip2 Crystals, Timothy D. Gustafson, Nancy C. Giles, Elizabeth M. Scherrer, Kevin T. Zawilski, Peter G. Schunemann, Kent L. Averett, Jonathan E. Slagle, Larry E. Halliburton

Faculty Publications

CdSiP2 crystals are used in optical parametric oscillators to produce tunable output in the mid-infrared. As expected, the performance of the OPOs is adversely affected by residual optical absorption from native defects that are unintentionally present in the crystals. Electron paramagnetic resonance (EPR) identifies these native defects. Singly ionized silicon vacancies (V-Si) are responsible for broad optical absorption bands peaking near 800, 1033, and 1907 nm. A fourth absorption band, peaking near 630 nm, does not involve silicon vacancies. Exposure to 1064 nm light when the temperature of the CdSiP2 crystal is near 80K converts …


The Top Ten Scientific Questions In Electrochemistry, Chinese Society of Electrochemistry 2024 Chinese Chemical Society | Xiamen University

The Top Ten Scientific Questions In Electrochemistry, Chinese Society Of Electrochemistry

Journal of Electrochemistry

No abstract provided.


Machine Learning For Electronic Structure Prediction, Shashank Pathrudkar 2024 Michigan Technological University

Machine Learning For Electronic Structure Prediction, Shashank Pathrudkar

Dissertations, Master's Theses and Master's Reports

Kohn-Sham density functional theory is the work horse of computational material science research. The core of Kohn-Sham density functional theory, the Kohn-Sham equations, output charge density, energy levels and wavefunctions. In principle, the electron density can be used to obtain several other properties of interest including total potential energy of the system, atomic forces, binding energies and electric constants. In this work we present machine learning models designed to bypass the Kohn-Sham equations by directly predicting electron density. Two distinct models were developed: one tailored to predict electron density for quasi one-dimensional materials under strain, while the other is applicable …


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