Semiconductor and Optical Materials Commons^™

Paper-Based Point-Of-Care Tools For Blood Testing, Xuefei Gao

Graduate Theses, Dissertations, and Problem Reports (ETD)

Early detection of malignant disease is crucial for timely diagnosis and effective medical intervention, which significantly increases survival rates and reduce financial burden on patients. Biomarkers are becoming increasingly important in detection of malignant diseases, because they can be employed for indicating diseases, predicting risks and monitoring the progression of diseases. In addition, biomarkers show up at early stages of diseases in human tissues and fluids (e.g., blood, urine and saliva), which shows great promise for early disease detection. In this dissertation, paper-based lateral flow strips (PLFSs) have been developed for the detection of disease biomarkers, including protein biomarkers and …

Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle

Theses and Dissertations--Chemistry

This project was motivated by an in situ heating experiment in the transmission electron microscope (TEM) in which gold (Au) nanoparticles were observed to dissolve tin dioxide (SnO2) nanowires (NWs) under vacuum. The explanation for this observation was that the high-temperature and low-pressure environment of the TEM caused the reverse reaction of the well-known vapor-liquid-solid (VLS) method commonly used to grow NWs. In the VLS process, a metal catalyst absorbs reactant vapor until it becomes supersaturated. The precipitation of the NW occurs at the liquid-solid interface, which ceases when there is no longer reactant vapor, and the diameter of the …

Studies Of Initial Growth Of Gan On Inn, Alaa Alnami

Graduate Theses and Dissertations

III-nitride materials have recently attracted much attention for applications in both the microelectronics and optoelectronics. For optoelectronic devices, III-nitride materials with tunable energy band gaps can be used as the active region of devices to enhance the absorption or emission. A such material is indium nitride (InN), which along with gallium nitride (GaN) and aluminum nitride (AlN) embody the very real promise of forming the basis of a broad spectrum, a high efficiency solar cell. One of the remaining complications in incorporating InN into a solar cell design is the effects of the high temperature growth of the GaN crystal …

Correlated Optical Imaging And Electrochemical Recording For Studying Single Nanoparticle Collisions, Lin-Lin Sun, Wei Wang, Hong-Yuan Chen

Journal of Electrochemistry

With the development of nano-fabrications in recent years, a novel strategy based on random collisions of single electroactive nanoparticles (NPs) onto an inert ultramicroelectrode (UME) has been emerged in the field of nanoelectrochemistry, and named as single nanoparticles collisions (SNCs). The technique uses a chronoamperometric method to detect transient current generated by random collisions of single NPs onto an UME. By analyzing the current signal, one could study the properties of single NPs. Although this technique can detect electrochemical or electrocatalytic currents of a single NP, the traditional SNCs technology lacks necessary spatial resolution to identify and characterize a specific …

Plasmonic Properties Of Nanoparticle And Two Dimensional Material Integrated Structure, Desalegn Tadesse Debu

Graduate Theses and Dissertations

Recently, various groups have demonstrated nano-scale engineering of nanostructures for optical to infrared wavelength plasmonic applications. Most fabrication technique processes, especially those using noble metals, requires an adhesion layer. Previously proposed theoretical work to support experimental measurement often neglect the effect of the adhesion layers. The first finding of this work focuses on the impact of the adhesion layer on nanoparticle plasmonic properties. Gold nanodisks with a titanium adhesion layer are investigated by calculating the scattering, absorption, and extinction cross-section with numerical simulations using a finite difference time domain (FDTD) method. I demonstrate that a gold nanodisk with an adhesive …

Scanning Probe Microscopy Measurements On 2d Materials And Iridates, Armin Ansary

Theses and Dissertations--Physics and Astronomy

In the past two decades, there has been a quest to understand and utilize novel materials such as iridates and two-dimensional (2D) materials. These classes of materials show a lot of interesting properties both in theoretical predictions as well as experimental results. Physical properties of some of these materials have been investigated using scanning probe measurements, along with other techniques.

One-dimensional (1D) catalytic etching was investigated in few-layer hexagonal boron nitride (hBN) films. Etching of hBN was shown to share several similarities with that of graphitic films. As in graphitic films, etch tracks in hBN commenced at film edges and …

Engineering Plasmonic Nanostructures For Light Management And Sensing, Sujan Phani Kumar Kasani

Graduate Theses, Dissertations, and Problem Reports (ETD)

The two major global problems are to provide health safety and to meet energy demands for ever growing population on a large scale. The study of light interaction with nanostructures has shown a promising solution in improving the fields of bio-sensor and solar energy devices which addresses above mentioned two major global problems. Nanostructures have tunable physicochemical properties such as light absorption, electrical and thermal properties unlike bulk materials, which gives an advantage in applications like bio-sensing and energy harvesting devices. The development of nanofabrication techniques along with the discovery of Surface Enhanced Raman Scattering (SERS) and Plasmon Enhanced Fluorescence …

Voltage-Controlled Deposition Of Nanoparticles For Next Generation Electronic Materials, Subhodip Maulik

LSU Doctoral Dissertations

This work presents both a feasibility study and an investigation into the voltage-controlled spray deposition of different nanoparticles, namely, carbon nanotubes (CNTs), as well as molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) from the transition metal dichalcogenides (TMDCs) family of materials. The study considers five different types of substrates as per their potential application to next-generation device electronics. The substrates selected for this research were: 1) aluminum as a conducting substrate, 2) silicon as a semiconducting substrate, 3) glass, silicon dioxide (SiO₂), and syndiotactic poly methyl methacrylate (syndiotactic PMMA) as insulating substrates.

Since the …

Glucose Level Estimation Based On Invasive Electrochemical, And Non-Invasive Optical Sensing Methods, Sanghamitra Mandal

Graduate Theses and Dissertations

The purpose of this research is to design and fabricate sensors for glucose detection using inexpensive approaches. My first research approach is the fabrication of an amperometric electrochemical glucose sensor, by exploiting the optical properties of semiconductors and structural properties of nanostructures, to enhance the sensor sensitivity and response time. Enzymatic electrochemical sensors are fabricated using two different mechanisms: (1) the low-temperature hydrothermal synthesis of zinc oxide nanorods, and (2) the rapid metal-assisted chemical etching of silicon (Si) to synthesize Si nanowires. The concept of gold nano-electrode ensembles is then employed to the sensors in order to boost the current …

Design, Fabrication, And Characterization Of All-Inorganic Quantum Dot Light Emitting Diodes, Ramesh Vasan

Graduate Theses and Dissertations

Quantum dot light emitting diodes are investigated as a replacement to the existing organic light emitting diodes that are commonly used for thin film lighting and display applications. In this, all-inorganic quantum dot light emitting diodes with inorganic quantum dot emissive layer and inorganic charge transport layers are designed, fabricated, and characterized. Inorganic materials are more environmentally stable and can handle higher current densities than organic materials. The device consists of CdSe/ZnS alloyed core/shell quantum dots as the emissive layer and metal oxide charge transport layer. The charge transport in these devices is found to occur through resonant energy transfer …

Phase Transitions In Monochalcogenide Monolayers, Mehrshad Mehboudi

Graduate Theses and Dissertations

Since discovery of graphene in 2004 as a truly one-atom-thick material with extraordinary mechanical and electronic properties, researchers successfully predicted and synthesized many other two-dimensional materials such as transition metal dichalcogenides (TMDCs) and monochalcogenide monolayers (MMs). Graphene has a non-degenerate structural ground state that is key to its stability at room temperature. However, group IV monochalcogenides such as monolayers of SnSe, and GeSe have a fourfold degenerate ground state. This degeneracy in ground state can lead to structural instability, disorder, and phase transition in finite temperature. The energy that is required to overcome from one degenerate ground state to another …

Investigation Of Nanomaterial Based Photovoltaic Panel Packaging Materials, Xingeng Yang

Graduate Theses and Dissertations

In this research, nanomaterial-based packaging materials for photovoltaic (PV) panels are investigated. A hydrophobic/anti-reflective surface coating which not only repels water from the top glass of a PV panel but at the same time reduces its light reflectance is investigated. COMSOL simulation results indicate that taller ellipsoid rod (aspect ratio = 5) reflects less light than shorter rod (aspect ratio = 0.5) in the desired spectrum for solar energy harvest from 400nm-700nm. The addition of a polymer layer on these ellipsoid rods broadens the light incident angle from 23° to 34°, from which light can be efficiently absorbed. Based on …

From Flasks To Applications: Design And Optimization Of Giant Quantum Dots Using Traditional And Automated Synthetic Methods, Christina J. Hanson

Nanoscience and Microsystems ETDs

Semiconducting nanocrystals, also known as quantum dots (QDs), that emit light with near-unity quantum yield and are extremely photostable are attractive options as down-conversion and direct electricity-to-light materials for a variety of applications including solid-state lighting, display technologies, bio-imaging and optical tracking. Standard QDs with a core/thin shell structure display fluorescence intermittency (blinking) and photobleaching when exposed to prolonged room temperature excitation for single dot measurements, as well as significant reabsorption and energy transfer when densely packed into polymers or at high solution concentrations.

We have developed thick shell “giant” QDs (gQDs), ultra-stable photon sources both at the ensemble and …

Nanostructured Materials Derived From Metal-Organic Frameworks For Energy And Environmental Applications, Zhiqiang Xie

LSU Doctoral Dissertations

Nowadays, energy and environmental issues have become the top priority among a series of global issues. Fossil fuels as the dominant source are depleted fast and usually lead to some environmental problems. Heavy metal pollution has posed a severe threat to environment and public health. Metal-organic frameworks (MOFs), as a very promising category of porous materials, have attracted more and more interest in research communities due to their extremely high surface areas, diverse nanostructures and unique properties. To meet the ever-increasing energy demand and tackle the heavy metal pollution in water, MOFs can function as ideal templates to prepare various …

Swelling As A Stabilizing Mechanism During Ion Bombardment Of Thin Films: An Analytical And Numerical Study, Jennifer M. Swenson

Mathematics Theses and Dissertations

Irradiation of semiconductor surfaces often leads to the spontaneous formation of rippled structures at certain irradiation angles. However, at high enough energies, these structures are observed to vanish for all angles, despite the absence of any identified, universally-stabilizing physical mechanisms in operation. Here, we examine the effect on pattern formation of radiation-induced swelling, which has been excluded from prior treatments of stress in irradiated films. After developing a suitable continuum model, we perform a linear stability analysis to determine its effect on stability. Under appropriate simplifying assumptions, we find swelling indeed to be stabilizing at wavenumbers typical of experimental observations. …

Block Copolymer Nanostructures For Inorganic Oxide Nanopatterning, Krishna Pandey

Graduate Theses/Dissertations

Self-assembled nature of block copolymer (BCP) makes them ideal for emerging technologies in nanometer scale. The micro phase separation between two or more dissimilar polymer blocks of BCP leads to uniform periodic nanostructures of different domains of dimension in the range of 5-100 nm, good for the development of emerging microelectronic and optoelectronics devices. Molecular weight and chain architecture of each blocks govern the morphology evolution; gives different structure like spherical, micelles, lamellae, cylindrical, gyroid etc. The morphology evolution of BCP nanostructure also depends on different external factors as well. In the first work of this thesis, three external factors …

Structural And Elastic Properties Of Degenerate Sno Monolayers At Finite Temperature, Afsana Sharmin

Graduate Theses and Dissertations

Chalcogen-based layered superconductors with a litharge structure such as FeS and FeSe mono-layers undergo structural and superconducting phase transitions that are tunable by doping. Representing another material platform with a litharge structure but without valence d-electrons, SnO monolayers also display a structural ground state with a degenerate rectangular unit cell at zero temperature and a charge-tunable energy barrier that leads to a thermally-controllable structural phase change. Doped SnO monolayers with rectangular degenerate unit cells give rise to two-dimensional multiferroicity. Their two-dimensional elastic energy landscape adopts a basic analytic expression that is employed to discuss this structural transition. The results contained …

Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, complex anisotropic materials are investigated and characterized by generalized ellipsometry. In recent years, anisotropic materials have gained considerable interest for novel applications in electronic and optoelectronic devices, mostly due to unique properties that originate from reduced crystal symmetry. Examples include white solid-state lighting devices which have become ubiquitous just recently, and the emergence of high-power, high-voltage electronic transistors and switches in all-electric vehicles. The incorporation of single crystalline material with low crystal symmetry into novel device structures requires reconsideration of existing optical characterization approaches. Here, the generalized ellipsometry concept is extended to include applications for materials with …

Nanowire-Based Light-Emitting Diodes: A New Path Towards High-Speed Visible Light Communication, Mohsen Nami

Physics & Astronomy ETDs

Nano-scale optoelectronic devices have gained significant attention in recent years. Among these devices are semiconductor nanowires, whose dimeters range from 100 to 200 nm. Semiconductor nanowires can be utilized in many different applications including light-emitting diodes and laser diodes. Higher surface to volume ratio makes nanowire-based structures potential candidates for the next generation of photodetectors, sensors, and solar cells. Core-shell light-emitting diodes based on selective-area growth of gallium nitride (GaN) nanowires provide a wide range of advantages. Among these advantages are access to non-polar m-plane sidewalls, higher active region area compared to conventional planar structures, and reduction of threading …

Atomistic Simulations Of Novel Nanoscale Semiconductor Devices: Resistance Switches And Two-Dimensional Transistors, Joseph P. Anderson, Mahbubul Islam, David Guzman, Alejandro Strachan

The Summer Undergraduate Research Fellowship (SURF) Symposium

As transistors get smaller, we are achieving record levels of memory density. However, there is a limit to how small transistors can be made before their functionality breaks down. Thus alternatives to traditional transistor technology are needed. The two such technologies we examined are: resistance switching devices, which reversibly grow metal filaments through a dielectric, and two-dimensional transistors, which are capable of breaking through the scalability limit of traditional transistors. In order to design resistance switching devices which create filaments with some level of consistency, the dynamics of the filament formation need to be explored. Herein we model this process …

Understanding Photovoltaic Properties Of Pbs Quantum Dot Solids Via Solution Contacting, Vitalii Dereviankin, Erik Johansson

Student Research Symposium

Photovoltaic (PV) devices based on PbS quantum dot (QD) solids demonstrate high photontoelectron conversion yields. However, record power conversion efficiency remain low, in part due to small photovoltages, which in turn are affected by both bulk and interfacial defects. Their relative impacts on limiting the photovoltaic performance of QD solids are not known. Interfacial defects can be formed when contacting a semiconductor and may dominate the semiconductor/metal or metaloxide junction properties. The objective of this study is to explore whether electrochemical contacting using liquid electrolytes provides means of contacting QD solids without introducing interfacial defects. We have initially focused on …

Infrared Energy Conversion In Plasmonic Fields At Two-Dimensional Semiconductors, Gregory Thomas Forcherio

Graduate Theses and Dissertations

Conversion of infrared energy within plasmonic fields at two-dimensional, semiconductive transition metal dichalcogenides (TMD) through plasmonic hot electron transport and nonlinear frequency mixing has important implications in next-generation optoelectronics. Drude-Lorentz theory and approximate discrete dipole (DDA) solutions to Maxwell’s equations guided metal nanoantenna design towards strong infrared localized surface plasmon resonance (LSPR). Excitation and damping dynamics of LSPR in heterostructures of noble metal nanoantennas and molybdenum- or tungsten-disulfide (MoS2; WS2) monolayers were examined by parallel synthesis of (i) DDA electrodynamic simulations and (ii) near-field electron energy loss (EELS) and far-field optical transmission UV-vis spectroscopic measurements. Susceptibility to second-order nonlinear frequency …

Plasmon-Mediated Energy Conversion In Metal Nanoparticle-Doped Hybrid Nanomaterials, Jeremy Dunklin

Graduate Theses and Dissertations

Climate change and population growth demand long-term solutions for clean water and energy. Plasmon-active nanomaterials offer a promising route towards improved energetics for efficient chemical separation and light harvesting schemes. Two material platforms featuring highly absorptive plasmonic gold nanoparticles (AuNPs) are advanced herein to maximize photon conversion into thermal or electronic energy. Optical extinction, attributable to diffraction-induced internal reflection, was enhanced up to 1.5-fold in three-dimensional polymer films containing AuNPs at interparticle separations approaching the resonant wavelength. Comprehensive methods developed to characterize heat dissipation following plasmonic absorption was extended beyond conventional optical and heat transfer descriptions, where good agreement was …

Fabrication And Study Of The Structure And Magnetism Of Rare-Earth Free Nanoclusters, Bhaskar Das

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

No abstract provided.

Single Molecule-Level Study Of Donor-Acceptor Interactions And Nanoscale Environment In Blends, Nicole Quist, Rebecca Grollman, Jeremy Rath, Alex Robertson, Michael Haley, John E. Anthony, Oksana Ostroverkhova

Chemistry Faculty Publications

Organic semiconductors have attracted considerable attention due to their applications in low-cost (opto)electronic devices. The most successful organic materials for applications that rely on charge carrier generation, such as solar cells, utilize blends of several types of molecules. In blends, the local environment strongly influences exciton and charge carrier dynamics. However, relationship between nanoscale features and photophysics is difficult to establish due to the lack of necessary spatial resolution. We use functionalized fluorinated pentacene (Pn) molecule as single molecule probes of intermolecular interactions and of the nanoscale environment in blends containing donor and acceptor molecules. Single Pn donor (D) molecules …

Fabrication Of Flexible, Biofunctional Architectures From Silk Proteins, Ramendra K. Pal

Theses and Dissertations

Advances in the biomedical field require functional materials and processes that can lead to devices that are biocompatible, and biodegradable while maintaining high performance and mechanical conformability. In this context, a current shift in focus is towards natural polymers as not only the structural but also functional components of such devices. This poses material-specific functionalization and fabrication related questions in the design and fabrication of such systems. Silk protein biopolymers from the silkworm show tremendous promise in this regard due to intrinsic properties: mechanical performance, optical transparency, biocompatibility, biodegradability, processability, and the ability to entrap and stabilize biomolecules. The unique …

Synthesis, Characterization, And Fabrication Of All Inorganic Quantum Dot Leds, Haider Baqer Salman

Graduate Theses and Dissertations

Quantum Dot LEDs with all inorganic materials are investigated in this thesis. The research was motivated by the potential disruptive technology of core shell quantum dots in lighting and display applications. These devices consisted of three main layers: hole transport layer (HTL), electron transport layer (ETL), and emissive layer where the emission of photons occurs. The latter part was formed of CdSe / ZnS core-shell quantum dots, which were synthesized following hot injection method. The ETL and the HTL were formed of zinc oxide nanocrystals and nickel oxide, respectively. Motivated by the low cost synthesis and deposition, NiO and ZnO …

Preparations And Photoelectrochemical Properties Of Phosphate Modified Rgo-Biobr Nanocomposites, Shuang-Ying Chen, Zhi-Jun Li, Xu-Liang Zhang, Kang Hu, Rui Yan, Li-Qiang Jing

Journal of Electrochemistry

The RGO-BiOBr nanocomposites have been successfully synthesized by a hydrothermal process, and then modified with phosphorous acids. The photoelectrochemical properties of the fabricated RGO-BiOBr nanocomposite films were studied. The results indicate that the photocurrent densities of RGO-BiOBr were much larger compared with those of the bare BiOBr, and interestingly, the photocurrent densities were further improved after phosphate modification. Based on the analyses of the produced hydroxyl radical amounts, the enhanced photocurrent densities could be attributed to the introduction of RGO and to the formed negative fields of modified phosphate groups, which are favorable for electrons to be transferred and for …

Contact Radius And Insulator-Metal Transition In Films Comprised Of Touching Semiconductor Nanocrystals, Deanna M. Lanigan

McKelvey School of Engineering Graduate Student Theses & Dissertations

Nanocrystal assemblies are being explored for a number of optoelectronic applications such as transparent conductors, photovoltaic solar cells, and electrochromic windows. Majority carrier transport is important for these applications, yet it remains relatively poorly understood in films comprised of touching nanocrystals. Specifically, the underlying structural parameters expected to determine the transport mechanism have not been fully elucidated. In this report, we demonstrate experimentally that the contact radius, between touching heavily doped ZnO nanocrystals, controls the electron transport mechanism. Spherical nanocrystals are considered, which are connected by a circular area. The radius of this circular area is the contact radius. For …

Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell

Electronic Theses and Dissertations

Photoelectrochemical water splitting has been identified as a promising route for achieving sustainable energy future. However, semiconductor materials with the appropriate optical, electrical and electrochemical properties have yet to be discovered. In search of an appropriate semiconductor to fill this gap, GaSbP, a semiconductor never tested for PEC performance is proposed here and investigated. Density functional theory (DFT+U) techniques were utilized to predict band gap and band edge energetics for GaSbP alloys with low amount of antimony. The overall objective of this dissertation is to understand the suitability of GaSb_xP_1-x alloys for photoelectrochemical water splitting application. Specifically, …