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University of Arkansas, Fayetteville

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Full-Text Articles in Materials Science and Engineering

Recovery And Evaluation Of A Germanium Infrared Camera, Michael Paszek May 2026

Recovery And Evaluation Of A Germanium Infrared Camera, Michael Paszek

Graduate Theses and Dissertations

Short-wave infrared imagers made of germanium are a promising way to extend silicon-compatible imaging beyond the visible spectrum. They also use mature CMOS fabrication and readout electronics. This thesis details the recovery, initialization, and evaluation of a germanium focal plane array (FPA) infrared camera system using both a sealed TriWave camera and a modular prototype platform. Functionality was restored to this legacy hardware, and repeatable testing workflows were established for evaluating packaged infrared imagers under controlled indoor and outdoor conditions. The prototype used a custom software interface named Merlott for evaluation, and it followed a standard sequence that included checking …

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Study On The Effects Of Molecular Layer Deposition Coating And Mechanical Pressure On Lithium Metal Anodes, Cameron Mondl May 2026

Study On The Effects Of Molecular Layer Deposition Coating And Mechanical Pressure On Lithium Metal Anodes, Cameron Mondl

Graduate Theses and Dissertations

Lithium (Li) metal is a highly promising anode material for next-generation energy storage systems due to its outstanding theoretical capacity and low electrochemical potential. However, its commercialization implementation has been hindered due to interfacial instability and uncontrollable dendrite formation, leading to poor cycling efficiency and thermal runaway. Among the most promising stabilization strategies, protective interfacial coatings have emerged as an effective solution to promote more uniform Li deposition and suppress erratic morphological inconsistencies. In particular, molecular layer deposition (MLD) enables uniform film thickness through layer-by-layer deposits, offering a highly versatile approach to protective interfacial layers. In addition to interfacial engineering, …

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Optical Characterization Of Ge And Gesn Grown In Aspect Ratio Trapping Structures For Enhanced Emitter Performance, Abdulla Said Ali Dec 2025

Optical Characterization Of Ge And Gesn Grown In Aspect Ratio Trapping Structures For Enhanced Emitter Performance, Abdulla Said Ali

Graduate Theses and Dissertations

Silicon (Si) began dominating the electronics industry since 1960s, the dominance came due to its affordability and well developed fabrication processes. But when it comes to light emitting devices and photonics devices in general, the indirect bandgap of Si has caused many scientists to search for alternative semiconductor materials that can deliver better light emission, materials that can also improve wavelengths detection which is also very limited when it comes to Si, reduce losses and greater light amplification, all this while still being affordable. Despite these limitations, Si has been widely used in Complementary Metal Oxide Semiconductor (CMOS) manufacturing and …

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Automation And Upgrading Of Custom Cold Wall Uhv-Cvd Reactor For Group Iv Material Development, Alexander Golden Dec 2025

Automation And Upgrading Of Custom Cold Wall Uhv-Cvd Reactor For Group Iv Material Development, Alexander Golden

Graduate Theses and Dissertations

Group IV alloys have shown promising results for infrared optoelectronic applications where III-V materials are currently dominant. The III-V material system has vacancies that Group IV materials can fill, most importantly complementary metal oxide semiconductor (CMOS) process compatibility making quality devices much cheaper and widely available compared to the current state of the art. Silicon, being an indirect band gap Group IV material, has poor performance in optoelectronic applications but is the dominant material for most of the electronic industry. However, when silicon is alloyed or substituted with other group IV materials, these optoelectronic properties can be enhanced and, in …

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Controlling Electroless Deposition On Polymer Interfaces Towards Discrete Functional Particle Synthesis, Grecia Pierina Alvarado Munoz Aug 2025

Controlling Electroless Deposition On Polymer Interfaces Towards Discrete Functional Particle Synthesis, Grecia Pierina Alvarado Munoz

Graduate Theses and Dissertations

Electroless deposition is a process that facilitates the formation of metal layers on surfaces through the reduction of metal ions onto a surface in the presence of a sacrificial reducing agent. This process can be applied to synthesize conductive metal layers on insulators such as glass or polymers. The kinetics of heterogeneous deposition depend on the interfacial surface chemistry, including the presence of added catalyst materials, as well as the bulk chemical environment, such as the concentration of metal ions and sacrificial reductants. Furthermore, the homogeneous formation of metal nanoparticles may compete with the deposition reaction, adversely affecting the control …

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Polymer-Enhanced Nanopore Sensing, Eugene Gyasi Agyemang Aug 2025

Polymer-Enhanced Nanopore Sensing, Eugene Gyasi Agyemang

Graduate Theses and Dissertations

The resistive pulse technique characterizes single analytes by detecting fluctuations in the ion current as they pass through a narrow orifice connecting two electrolyte-filled chambers, each containing a single electrode. The amplitude, shape, frequency, and duration of these fluctuations primarily provide information about the analyte’s size, shape, concentration, and net surface charge, respectively. One configuration for resistive pulse measurements is of an electrolyte-filled nanopipette immersed in a bath, where the nanopipette tip acts as the nanoscale orifice. It was previously shown that incorporating the large quantities polymer polyethylene glycol (PEG 8K, 50% w/v) into the external electrolyte bath dramatically enhanced …

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Synthesis, Structural Characterization And Optical Studies Of Silver-Indium-(Zinc)-Chalcogenide Fluorescent Quantum Dots, Sujal Acharya Aug 2025

Synthesis, Structural Characterization And Optical Studies Of Silver-Indium-(Zinc)-Chalcogenide Fluorescent Quantum Dots, Sujal Acharya

Graduate Theses and Dissertations

Developing a non-toxic, high-performance fluorescent nanomaterial is crucial for overcoming the environmental and health restrictions of current cadmium, and lead based quantum dots (QDs), which limit the application of quantum dots in optoelectronics and bioimaging. In this thesis, we synthesized environmentally friendly AgInS2 QDs by a colloidal method, systematically altering the In/Ag precursor ratio from 2 to 6 to study the impact on their optical and photophysical properties. Our goals were to find the optimal stoichiometry for maximum quantum efficiency and stability. We also investigated further improving optical and photophysical properties through shelling with ZnS. The emission spectra appeared broad, …

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Defect Characterization Of Sic Schottky Barrier Diode Using Deep Level Transient Spectroscopy, Zachary I. Mccoy May 2025

Defect Characterization Of Sic Schottky Barrier Diode Using Deep Level Transient Spectroscopy, Zachary I. Mccoy

Electrical Engineering and Computer Science Undergraduate Honors Theses

The aim of this project is to use deep level transient spectroscopy (DLTS) to energetically evaluate defects by using the carrier concentration dependence on temperature and where these carriers may experience deviation from standard predictions. These defects become apparent through multiple C-V measurements that are swept through a temperature range. By analyzing trends with respect to temperature, the defects can be energetically “located,” and thus identified. This identification can help streamline semiconductor material manufacturing/growth because DLTS identifies potential defect causes by providing data to characterize semiconductor mid-band defects. DLTS can assess nearly all parameters associated with traps/defects including density, thermal …

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Multifunctional Pvdf Ionogels With Magnetic Nanoparticles For Electroactive And Magnetic Actuation, Alfredo Carrillo Valverde May 2025

Multifunctional Pvdf Ionogels With Magnetic Nanoparticles For Electroactive And Magnetic Actuation, Alfredo Carrillo Valverde

Chemical Engineering Undergraduate Honors Theses

The fast development of compact and multifunctional electronics has driven interest in smart materials capable of responding to multiple stimuli. Ionogels, polymers that have been swollen with ionic liquids (IL), offer several favorable electrochemical and thermal properties due to their intrinsic ion conductivity, wide electrochemical window, non-flammability, and high thermal stability. However, their poor mechanical properties (e.g., modulus and strength) limit their use in applications. In this work, multifunctional PVDF ionogel composites were made by blending magnetically responsive iron oxide nanoparticles (Fe3O4 MNPs) into the polymer matrix. The influence of MNP concentration (9-21 wt%) on composition, ionic …

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Flexible Microelectrode-Based Impedance Immunosensor For Rapid Detection Of E. Coli O157:H7, Sonatan Kumar Biswas May 2025

Flexible Microelectrode-Based Impedance Immunosensor For Rapid Detection Of E. Coli O157:H7, Sonatan Kumar Biswas

Graduate Theses and Dissertations

Abstract Food contamination poses a significant threat to public health, the economy, and human health worldwide, occurring at any stage of the food supply chain, from farm to fork. Escherichia coli 0157:H7, recognized as one of the principal causes of foodborne illness, poses a considerable risk to food safety. The primary objective of this investigation is to devise a flexible microelectrode-based immunosensor capable of swiftly identifying E. coli O157:H7 cells without the need for incubation in a pure culture environment. In the development of the biosensor, the gold electrode (composed of 50% Au) underwent an initial coating process involving 2-aminoethanethiol/cysteamine, …

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Characterizing Heating And Resistance Properties Of Nichrome Burn Wire To Be Used In Cubesat Actuation, Noah Moix May 2025

Characterizing Heating And Resistance Properties Of Nichrome Burn Wire To Be Used In Cubesat Actuation, Noah Moix

Mechanical Engineering Undergraduate Honors Theses

This thesis investigates the use of Nichrome 60 wire as a burn wire mechanism, commonly utilized in CubeSats and other aerospace engineering applications requiring precise, single-use release systems. The experiment focused on characterizing the thermal and resistive behavior of Nichrome 60 wire under Joule heating conditions. Four wire configurations were tested: 34-gauge and 36-gauge wires, each at lengths of 1 inch and 2 inches. Each configuration was subjected to a constant current until thermal failure occurred. During testing, real-time measurements of electrical resistance and wire temperature were recorded. This data was used to generate resistance vs. temperature profiles for each …

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Exploring Metal Additive Manufacturing In Martian Atmospheric Environments, Zane Mebruer May 2025

Exploring Metal Additive Manufacturing In Martian Atmospheric Environments, Zane Mebruer

Mechanical Engineering Undergraduate Honors Theses

On-surface manufacturing is key to the success of a planetary colonization, especially that of Mars. However, traditional subtractive manufacturing processes are equipment, energy, and material intensive, meaning novel additive manufacturing (AM) processes must be pursued for this end. Selective laser melting, one of the most effective and versatile AM methods, would be incredibly beneficial to a Martian mission but requires an artificial argon atmosphere to create effective parts. The purpose of this study was to examine if carbon dioxide, the gas that makes up over 95% of Mars’ surface atmosphere, would be a sufficient substitute for argon in SLM fabrication. …

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Thermal Characterization Of 3d Printing Materials For Increasing Insulation Potential And Practicality, Jackson H. Minnick May 2025

Thermal Characterization Of 3d Printing Materials For Increasing Insulation Potential And Practicality, Jackson H. Minnick

Mechanical Engineering Undergraduate Honors Theses

This study served as an exploration into the possible existence of a correlation between the infill lattice structure of a 3D printed wall section and the thermal performance of that sample as characterized by thermal conductivity measured in units of Watts per meter Kelvin. With the continual increase in the practicality, fidelity, and applicable fields of additive manufacturing, namely FDM 3D printing, research on specific print characteristics and their effects on the material and thermal characteristics of the part in question is steadily becoming more commonplace. Although the thermal conductivity of 3D printed wall sections as a function of infill …

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Modeling, Synthesis, And Experimental Characterization Of Rhenium Disulfide For Optoelectronic Devices, Solomon Opeyami Ojo Dec 2024

Modeling, Synthesis, And Experimental Characterization Of Rhenium Disulfide For Optoelectronic Devices, Solomon Opeyami Ojo

Graduate Theses and Dissertations

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have garnered considerable interest for their potential in optoelectronics and photonics owing to their remarkable combination of electronic, optical, and mechanical properties. These characteristics distinguish them from other 2D materials, including graphene, making them particularly valuable for next-generation technologies. This dissertation focuses on ReS₂, a 2D TMD with a unique anisotropic 1T distorted crystal structure. The research aims to elucidate its fundamental properties through a combination of theoretical modeling, material synthesis, and experimental characterization techniques, with the goal of optimizing ReS₂ for device applications. A theoretical investigation utilizing Density Functional Theory …

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Ohmic Contacts For Fabrication Of Sic Cmos Devices, Anthony Di Mauro Dec 2024

Ohmic Contacts For Fabrication Of Sic Cmos Devices, Anthony Di Mauro

Graduate Theses and Dissertations

Today’s world of electronics is dominated by semiconductor devices which utilize silicon as their substrate material. Though, silicon is not ideal for semiconductor devices in high-voltage or high-temperature applications. Additionally, the efficiency of silicon devices becomes drastically reduced in nonideal operating conditions. Therefore, finding alternatives to silicon?based devices has been a topic for decades now. A few great candidates to replace silicon devices for said applications include Silicon Carbide (SiC), Gallium Nitride (GaN), and Aluminum Arsenide (AlAs). SiC has grown its reputation as the best candidate, when compared to other potential alternatives, due to its wide bandgap, high operating frequency, …

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Investigating Functionalized Cvd Graphene Heterostructures As Platforms For Hydrogen Gas Sensing, Evans Asiedu Addo-Mensah Dec 2024

Investigating Functionalized Cvd Graphene Heterostructures As Platforms For Hydrogen Gas Sensing, Evans Asiedu Addo-Mensah

Graduate Theses and Dissertations

The hydrogen economy is rapidly advancing and is poised to become one of the world's largest economies, driven by the abundance of hydrogen gas. Several organizations, particularly in the United States of America, are closely or have been monitoring this development, with rapidly increasing interest. Considering that hydrogen gas has no taste, smell (odor), or color, and very combustible, it’s imperative to develop detectors and sensors capable of rapidly detecting leaks to prevent application disasters. Owing to its extraordinary mechanical and electrical characteristics, graphene is the material that has been studied the most. When combined with hexagonal boron nitride (hBN), …

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Liquid Crystalline Collagen Assemblies As Substrates For Directed Alignment Of Human Schwann Cells, Homa Ghaiedi, Luis Carlos Pinzon-Herrera, Saja Alshafeay, Leonard Harris, Jorge Almodovar, Karthik Nayani Nov 2024

Liquid Crystalline Collagen Assemblies As Substrates For Directed Alignment Of Human Schwann Cells, Homa Ghaiedi, Luis Carlos Pinzon-Herrera, Saja Alshafeay, Leonard Harris, Jorge Almodovar, Karthik Nayani

Chemical Engineering Faculty Publications and Presentations

Collagen is a key component of the extracellular matrix (ECM) and well-oriented domains of collagen are important for mimicking the local cell environment in vitro. While there has been significant attention directed towards the alignment of collagen, formation of large-scale oriented domains remains a key challenge. Type I collagen self-assembles to form liquid crystalline (LC) mesophases in acidic conditions at concentrations above 100 mg mL−1. The LC mesophase provides an efficient platform for large-scale alignment and patterning of collagen coated substrates. However, there still exist challenges related to solubilizing and processing of collagen at such high concentrations in order …

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Insulator-To-Metal Transition And Isotropic Gigantic Magnetoresistance In Layered Magnetic Semiconductors, Gokul Acharya, Bimal Neupane, Chia-Hsiu Hsu, Xian P. Yang, David Graf, Eun Sang Choi, Krishna Pandey, Md Rafique Un Nabi, Santosh Karki Chhetri, Rabindra Basnet, Sumaya Rahman, Jian Wang, Zhengxin Hu, Bo Da, Hugh O.H. Churchill, Guoqing Chang, M. Zahid Hasan, Yuanxi Wang, Jin Hu Nov 2024

Insulator-To-Metal Transition And Isotropic Gigantic Magnetoresistance In Layered Magnetic Semiconductors, Gokul Acharya, Bimal Neupane, Chia-Hsiu Hsu, Xian P. Yang, David Graf, Eun Sang Choi, Krishna Pandey, Md Rafique Un Nabi, Santosh Karki Chhetri, Rabindra Basnet, Sumaya Rahman, Jian Wang, Zhengxin Hu, Bo Da, Hugh O.H. Churchill, Guoqing Chang, M. Zahid Hasan, Yuanxi Wang, Jin Hu

Physics Faculty Publications and Presentations

Magnetotransport, the response of electrical conduction to external magnetic field, acts as an important tool to reveal fundamental concepts behind exotic phenomena and plays a key role in enabling spintronic applications. Magnetotransport is generally sensitive to magnetic field orientations. In contrast, efficient and isotropic modulation of electronic transport, which is useful in technology applications such as omnidirectional sensing, is rarely seen, especially for pristine crystals. Here a strategy is proposed to realize extremely strong modulation of electron conduction by magnetic field which is independent of field direction. GdPS, a layered antiferromagnetic semiconductor with resistivity anisotropies, supports a field-driven insulator-to-metal transition …

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Lithicone-Protected Lithium Metal Anodes For Lithium Metal Batteries With Nickel-Rich Cathode Materials, Ridwan A. Ahmed, Kevin V. Carballo, Krishna P. Koirala, Qian Zhao, Peiyuan Gao, Ju-Myung Kim, Cassidy S. Anderson, Xiangbo Meng, Chongmin Wang, Ji-Guang Zhang, Wu Xu Nov 2024

Lithicone-Protected Lithium Metal Anodes For Lithium Metal Batteries With Nickel-Rich Cathode Materials, Ridwan A. Ahmed, Kevin V. Carballo, Krishna P. Koirala, Qian Zhao, Peiyuan Gao, Ju-Myung Kim, Cassidy S. Anderson, Xiangbo Meng, Chongmin Wang, Ji-Guang Zhang, Wu Xu

Mechanical Engineering Faculty Publications and Presentations

The high energy density advantage of lithium (Li) metal batteries (LMBs) makes them increasingly desirable; however, problems such as strong reactivity and dendrite growth of Li metal anode limit their practical uses. In this work, a novel Li-containing glycerol (LiGL) or lithicone protection layer on a 50 μm thick Li metal anode is employed for improving the performance of LMBs. This LiGL layer was accurately deposited via a molecular layer deposition (MLD) process at 150°C, using lithium tert-butoxide and glycerol as precursors. The as-formed LiGL coating layer is highly tunable in its thickness by simply adjusting MLD cycles and shows …

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Substrate Interference And Strain In The Second-Harmonic Generation From Mose2 Monolayers, Sudeep Puri, Sneha Patel, Jose Luis Cabellos, Luis Enrique Rosas-Hernandez, Kaitlin Reynolds, Hugh O.H. Churchill, Salvador Barraza-Lopez, Bernardo S. Mendoza, Hiroyuki Nakamura Oct 2024

Substrate Interference And Strain In The Second-Harmonic Generation From Mose2 Monolayers, Sudeep Puri, Sneha Patel, Jose Luis Cabellos, Luis Enrique Rosas-Hernandez, Kaitlin Reynolds, Hugh O.H. Churchill, Salvador Barraza-Lopez, Bernardo S. Mendoza, Hiroyuki Nakamura

Physics Faculty Publications and Presentations

Nonlinear optical materials of atomic thickness, such as non-centrosymmetric 2H transition metal dichalcogenide monolayers, have a second-order nonlinear susceptibility (χ(2)) whose intensity can be tuned by strain. However, whether χ(2) is enhanced or reduced by tensile strain is a subject of conflicting reports. Here, we grow high-quality MoSe2 monolayers under controlled biaxial strain created by two different substrates and study their linear and nonlinear optical responses with a combination of experimental and theoretical approaches. Up to a 15-fold overall enhancement in second-harmonic generation (SHG) intensity is observed from MoSe2 monolayers grown on SiO2 when …

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First-Principles Simulation Of The Interaction Between Dna Nucleotides And One-Dimensional Carbon Chain In Electrical Based Sequencing, Zeina Salman, Jin-Woo Kim, Steve Tung Sep 2024

First-Principles Simulation Of The Interaction Between Dna Nucleotides And One-Dimensional Carbon Chain In Electrical Based Sequencing, Zeina Salman, Jin-Woo Kim, Steve Tung

Biological and Agricultural Engineering Faculty Publications and Presentations

Electrical DNA sequencing has attracted significant attention in recent years due to its simplified sequencing protocol, compact sequencing system, and relatively low sequencing cost. In the design and fabrication of the sequencing device, carbon-based nanomaterials such as graphene have been explored as a promising sensing material that provides an excellent combination of spatial resolution and base specificity. Using first-principles simulation, we determined the effect on the electrical conductivity of a one-dimensional carbon chain due to the presence of four DNA bases. The simulation results indicate that the interaction between the carbon chain and different DNA bases leads to different levels …

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Development Of Tissue-Engineered Model Of Fibrotic Scarring After Spinal Cord Injury To Study Astrocyte Activation And Neurite Outgrowth In Vitro, Nikolas Ala-Kokko, Inha Baek, Younghye Song Sep 2024

Development Of Tissue-Engineered Model Of Fibrotic Scarring After Spinal Cord Injury To Study Astrocyte Activation And Neurite Outgrowth In Vitro, Nikolas Ala-Kokko, Inha Baek, Younghye Song

Biomedical Engineering Faculty Publications and Presentations

Traumatic spinal cord injuries (SCI) are debilitating injuries affecting twenty-seven million people worldwide and cause functional impairments. Despite decades of research and medical advancements, current treatment options for SCI remain limited, in part due to the complex pathophysiology of spinal cord lesions including cellular transformation and extracellular matrix (ECM) remodeling. Recent studies have increased focus on fibrotic scarring after SCI, and yet much remains unclear about the impact of fibrotic scarring on SCI lesion progression. Here, using collagen and decellularized spinal cord-based composite hydrogels, a three-dimensional (3D) cell culture model mimicking the fibrous core of spinal cord lesions was implemented …

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Settingsorder Article Reprints Open Accessarticle A Model To Account For The Effects Of Load Ratio And Hydrogen Pressure On The Fatigue Crack Growth Behavior Of Pressure Vessel Steels, Ashok Saxena, Kip O. Findley Aug 2024

Settingsorder Article Reprints Open Accessarticle A Model To Account For The Effects Of Load Ratio And Hydrogen Pressure On The Fatigue Crack Growth Behavior Of Pressure Vessel Steels, Ashok Saxena, Kip O. Findley

Mechanical Engineering Faculty Publications and Presentations

A phenomenological model for estimating the effects of load ratio R and hydrogen pressure PH2 on the hydrogen-assisted fatigue crack growth rate (HA-FCGR) behavior in the transient and steady-state regimes of pressure vessel steels is described. The "transient regime" is identified with crack growth within a severely embrittled zone of intense plasticity at the crack tip. The "steady-state" behavior is associated with the crack growing into a region of comparatively lower hydrogen concentration located further away from the crack tip. The model treats the effects of R and PH2 as being functionally separable. In the transient …

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Enhanced Optical And Infrared Activity Of Nanosphere Dimers Attributed To Dimer Geometry, D. Keith Roper, Jin-Woo Kim, Ricardo R. Romo, Joseph Batta-Mpouma Aug 2024

Enhanced Optical And Infrared Activity Of Nanosphere Dimers Attributed To Dimer Geometry, D. Keith Roper, Jin-Woo Kim, Ricardo R. Romo, Joseph Batta-Mpouma

Biological and Agricultural Engineering Faculty Publications and Presentations

Enhanced optical and infrared activity of subwavelength metal nanoparticles is key to their use in optoelectronics, spectroscopy, and sensing. The present work compared spectra of nanosphere dimers merged by centrifuging gold nanospheres with corresponding simulated nanoscale dimers. Geometric features of the nanosphere dimers were related to corresponding optical and near-infrared activity through simulation. Differences in optical and infrared activity of the nanosphere dimers were largely attributable to changes in the radius of the nanosphere and the radius of the conductive junction between merged nanospheres. The features observed in the experimental spectra were attributed to a select number of dimers exhibiting …

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Computational Alchemy: Pioneering Spintronic, Thermoelectric, And Optoelectronic Materials Design Through First-Principles Calculations And Machine Learning, Eesha Sanjay Andharia Aug 2024

Computational Alchemy: Pioneering Spintronic, Thermoelectric, And Optoelectronic Materials Design Through First-Principles Calculations And Machine Learning, Eesha Sanjay Andharia

Graduate Theses and Dissertations

Intelligent materials discovery and design plays a pivotal role in advancement of spintronics, optoelectronics and thermoelectric devices and technology. In this study, we investigate three types of materials using first principles calculations. First, the structural, electronic, and magnetic properties of CrTiCoZ (Z = Al, Si) equiatomic quaternary Heusler alloys were investigated. CrTiCoAl compound was found to exhibit a half metallic ferromagnetic structure and Curie temperature above room temperature, which makes it an ideal candidate for magnetic tunnel junction, the basic building block of Spintronic devices. Second, we use Green’s function to obtain the finite temperature phonons by including quartic anharmonicity …

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Modeling Study Of Si3N4 Waveguides On A Sapphire Platform For Photonic Integration Applications, Diandian Zhang, Shui-Qing Yu, Gregory J. Salamo, Richard A. Soref, Wei Du Aug 2024

Modeling Study Of Si3N4 Waveguides On A Sapphire Platform For Photonic Integration Applications, Diandian Zhang, Shui-Qing Yu, Gregory J. Salamo, Richard A. Soref, Wei Du

Electrical Engineering and Computer Science Faculty Publications and Presentations

Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with potentially high-performance lasers made of group III–V materials. In parallel with developing active devices for photonics integration applications, in this work, silicon nitride optical waveguides on a sapphire substrate were analyzed using the commercial software Comsol Multiphysics in a spectral window of 800~2400 nm, covering the operating wavelengths of III–V lasers, which could be monolithically or hybridly integrated on the same substrate. A high confinement factor of ~90% near the single-mode …

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Molecular Beam Epitaxy Of Gesn On Iii-V Substrates For Photonic Applications, Calbi Gunder Aug 2024

Molecular Beam Epitaxy Of Gesn On Iii-V Substrates For Photonic Applications, Calbi Gunder

Graduate Theses and Dissertations

This dissertation explores the advancement of germanium-tin (GeSn) as a tuneable narrow bandgap material, crucial for the development of high-efficiency photodetectors and laser devices in near- and mid-infrared technologies. We investigate the synthesis challenges, particularly the lattice mismatch between GeSn alloys and substrates, which significantly affects their crystalline and optical qualities. Through molecular beam epitaxy, we examine the growth of Ge and GeSn on GaAs (001) substrates, employing Ge/GaAs and Ge/AlAs buffer layers to investigate these challenges. Our findings, characterized by X-ray diffraction, atomic force microscopy, reflection high-energy electron diffraction, and photoluminescence, demonstrate the production of high-quality Ge layers, achieving …

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Performance And Enhanced Efficiency Induced By Cold Plasma On Sapo-34 Membranes For Co2 And Ch4 Mixtures, Fnu Gorky, Vashanti Storr, Grace Jones, Apolo Nambo, Jacek B. Jasinski, Maria L. Carreon Aug 2024

Performance And Enhanced Efficiency Induced By Cold Plasma On Sapo-34 Membranes For Co2 And Ch4 Mixtures, Fnu Gorky, Vashanti Storr, Grace Jones, Apolo Nambo, Jacek B. Jasinski, Maria L. Carreon

Chemical Engineering Faculty Publications and Presentations

In this study, we investigate the influence of cold-plasma-induced enhanced performance and efficiency of SAPO-34 membranes in the separation of CO2 and CH4 mixtures. Placing the herein presented research in a broader context, we aim to address the question of whether cold plasma can significantly impact the membrane performance. We subjected SAPO-34 membranes to plasma mild disturbances and analyzed their performance in separating CO2 and CH4. Our findings reveal a notable enhancement in membrane efficiency and sustained performance when exposed to cold plasma. The pulsed plasma separation displayed improved structural integrity, and the experimental results …

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Understanding And Tuning Magnetism In Van Der Waals-Type Metal Thiophosphates, Rabindra Basnet, Jin Hu Aug 2024

Understanding And Tuning Magnetism In Van Der Waals-Type Metal Thiophosphates, Rabindra Basnet, Jin Hu

Physics Faculty Publications and Presentations

Over the past two decades, significant progress in two-dimensional (2D) materials has invigorated research in condensed matter and material physics in low dimensions. While traditionally studied in three-dimensional systems, magnetism has now been extended to the 2D realm. Recent breakthroughs in 2D magnetism have attracted substantial interest from the scientific community, owing to the stable magnetic order achievable in atomically thin layers of the van der Waals (vdW)-type layered magnetic materials. These advances offer an exciting platform for investigating related phenomena in low dimensions and hold promise for spintronic applications. Consequently, vdW magnetic materials with tunable magnetism have attracted significant …

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Development Of Iii-V And Iv Epitaxy On Sapphire Technology, Emmanuel Wangila Aug 2024

Development Of Iii-V And Iv Epitaxy On Sapphire Technology, Emmanuel Wangila

Graduate Theses and Dissertations

This research presents comprehensive insights into the epitaxial growth of germanium (Ge) on c-plane sapphire substrates using molecular beam epitaxy (MBE). The direct growth of Ge on sapphire typically yields three-dimensional (3D) Ge islands with diverse growth directions, multiple primary domains, and twinned crystals. However, incorporating a thin AlAs nucleation layer proves instrumental in enhancing surface and material quality. With a 10 nm AlAs layer, the achieved surface exhibits improved characteristics, including a smoother surface, single epitaxial orientation, sharper rocking curve, and a single domain. This study surpasses previous works by achieving a single primary domain and reducing twinning. Furthermore, …

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