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Semiconductor and Optical Materials Commons™

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2016

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Articles 31 - 54 of 54

Full-Text Articles in Semiconductor and Optical Materials

Investigation Of Optical Properties Of Zinc Oxide Photodetector, Tyler Chism May 2016

Investigation Of Optical Properties Of Zinc Oxide Photodetector, Tyler Chism

Graduate Theses and Dissertations

UV photodetection devices have many important applications for uses in biological detection, gas sensing, weaponry detection, fire detection, chemical analysis, and many others. Today’s photodetectors often utilize semiconductors such as GaAs to achieve high responsivity and sensitivity. Zinc oxide, unlike many other semiconductors, is cheap, abundant, non-toxic, and easy to grow different morphologies at the micro and nano scale. With the proliferation of these devices also comes the impending need to further study optics and photonics in relation to phononics and plasmonics, and the general principles underlying the interaction of photons with solid state matter and, specifically, semiconductors. For this …

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Synthesis Of Acceptors For Use In Donor-Acceptor Copolymers And Characterization Of These Polymers, William D. Walker May 2016

Synthesis Of Acceptors For Use In Donor-Acceptor Copolymers And Characterization Of These Polymers, William D. Walker

Honors Theses

In this thesis, a selenium-derivatized acceptor was synthesized to examine the heavy atom effects of selenium on the position of the frontier molecular orbitals (HOMO/LUMO band gap) as opposed to sulfur in a donor-acceptor copolymer for use in light harvesting and detection applications. Over the course of this research, standard operating protocols for ultraviolet-visible (UV-Vis-NIR) and Fourier transform infrared (FT-IR) spectroscopies, as well as cyclic voltammetry (CV) characterization techniques were established. Once synthesized, the polymers were characterized through use of the established characterization protocols. The selenium-derivatized polymer exhibited a bathochromic shift compared to the sulfur analogue, with a solid-state absorption …

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Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell May 2016

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 GaSbxP1-x alloys for photoelectrochemical water splitting application. Specifically, …

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Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson May 2016

Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson

Electronic Theses and Dissertations

Scaling electronic devices has become paramount. The current work builds upon scaling efforts by developing novel synthesis methods and next generation sensing devices based on 2D materials. A new combination method utilizing thermal evaporation and chemical vapor deposition was developed and analyzed to show the possibilities of Transition Metal Dichalcogenide monolayers and heterostructures. The materials produced from the above process showed high degrees of compositional control in both spatial dimensions and chemical structure. Characterization shows controlled fabrication of heterostructures, which may pave the way for future band gap engineering possibilities. In addition, Phosphorene based field effect transistors, photodetectors, and gas …

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Palladium Nanoparticles On Zno-Passivated Carbon For Enhanced Performance In Li-O2 Batteries, Mar Piernavieja-Hermida Apr 2016

Palladium Nanoparticles On Zno-Passivated Carbon For Enhanced Performance In Li-O2 Batteries, Mar Piernavieja-Hermida

Research Horizons Day Posters

No abstract provided.

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Growth Of Ws2 Thin Photovoltaic Films, Matthew J. Hilfiker, Aaron Ediger, Natale Lanno Apr 2016

Growth Of Ws2 Thin Photovoltaic Films, Matthew J. Hilfiker, Aaron Ediger, Natale Lanno

UCARE: Research Products

Through research for a material that is low cost, earth abundant, and highly efficient, Tungsten Sulfide (WS2) has been identified as a promising solution. From literature, it has been shown that WS2 possesses a band gap of 1.9 eV, which is ideal for a top layer heterostructure cell. While this is a favorable value, other properties needed to understand its value as a photovoltaic material are unknown. Through research, WS2 films will be grown through a sputtering deposition process and electrical characterization measurements will be performed to study these missing properties.

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Identification Of The Zinc-Oxygen Divacancy In Zno Crystals, Maurio S. Holston, Eric M. Golden, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton Apr 2016

Identification Of The Zinc-Oxygen Divacancy In Zno Crystals, Maurio S. Holston, Eric M. Golden, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

An electron paramagnetic resonance (EPR) spectrum in neutron-irradiated ZnO crystals is assigned to the zinc-oxygen divacancy. These divacancies are observed in the bulk of both hydrothermally grown and seeded-chemical-vapor-transport-grown crystals after irradiations with fast neutrons. Neutral nonparamagnetic complexes consisting of adjacent zinc and oxygen vacancies are formed during the irradiation. Subsequent illumination below ∼150 K with 442 nm laser light converts these (V2−Zn − V2+O)0 defects to their EPR-active state (V−Zn − V2+O)+ as electrons are transferred to donors. The resulting photoinduced S = 1/2 spectrum of the …

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Plasma Processing Of Superconducting Radio Frequency Cavities, Janardan Upadhyay Apr 2016

Plasma Processing Of Superconducting Radio Frequency Cavities, Janardan Upadhyay

Physics Theses & Dissertations

The development of plasma processing technology of superconducting radio frequency (SRF) cavities not only provides a chemical free and less expensive processing method, but also opens up the possibility for controlled modification of the inner surfaces of the cavity for better superconducting properties. The research was focused on the transition of plasma etching from two dimensional flat surfaces to inner surfaces of three dimensional (3D) structures. The results could be applicable to a variety of inner surfaces of 3D structures other than SRF cavities. Understanding the Ar/Cl2 plasma etching mechanism is crucial for achieving the desired modification of Nb …

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Spin-Gapless Semiconductivity And Half Metallicity In Heusler Alloys, Bradley A. Staten, Pavel V. Lukashev Mar 2016

Spin-Gapless Semiconductivity And Half Metallicity In Heusler Alloys, Bradley A. Staten, Pavel V. Lukashev

Research in the Capitol

In recent years, ever increasing interest in spin-based electronics (spintronics) has resulted in the search for a new class of materials that can provide a high degree of transport spin polarization. An ideal candidate would act like insulator for one spin channel and a conductor or semiconductor for the opposite spin channel (e.g. half metals (HM), spin gapless semiconductors (SGS)). In this work, we present results of our computational and theoretical study (Staten, et al., J. Appl. Phys. 117, 17D115 (2015)) of Heusler compounds with potential commercial applications in the field of spintronics. We show that naturally these materials are …

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Semiconductor Film Grown On A Circular Substrate: Predictive Modeling Of Lattice-Misfit Stresses, Ephraim Suhir, Johann Nicolics, G. Khatibi, M. Lederer Mar 2016

Semiconductor Film Grown On A Circular Substrate: Predictive Modeling Of Lattice-Misfit Stresses, Ephraim Suhir, Johann Nicolics, G. Khatibi, M. Lederer

Mechanical and Materials Engineering Faculty Publications and Presentations

effective and physically meaningful analytical predictive model is developed for the evaluation the lattice-misfit stresses (LMS) in a semiconductor film grown on a circular substrate (wafer). The two-dimensional (plane-stress) theory-of-elasticity approximation (TEA) is employed in the analysis. The addressed stresses include the interfacial shearing stress, responsible for the occurrence and growth of dislocations, as well as for possible delaminations and the cohesive strength of a buffering material, if any. Normal radial and circumferential (tangential) stresses acting in the film cross-sections and responsible for its short- and long-term strength (fracture toughness) are also addressed. The analysis is geared to the GaN …

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Investigation Of Polyaniline And Its Composites As Interlayers In Organic Solar Cells, Omar Abdulrazzaq Al-Azzawi Feb 2016

Investigation Of Polyaniline And Its Composites As Interlayers In Organic Solar Cells, Omar Abdulrazzaq Al-Azzawi

Theses and Dissertations

Significant attention has been given during the last few years to overcoming technological and material barriers to the development of organic photovoltaic devices (OPVs) with cost efficiency comparable to that of inorganic photovoltaics (PVs). If OPVs are to become commercially viable, major improvements are necessary. In this work, polyaniline (PANI) protonated with various levels of camphorsulfonic acid (CSA) and dissolved in m-cresol has been used as a hole-transport layer (HTL) in organic bulk-heterojunction solar cells. Polyaniline was first synthesized using oxidative polymerization based on the MacDiarmid method. The polymerization parameters, such as polymerization temperature and polymerization pH control agent, were …

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Strain Effects On The Work Function Of An Organic Semiconductor, Yanfei Wu, Annabel R. Chew, Geoffrey A. Rojas, Gjergji Sini, Greg Haugstad, Alex Belianinov, Sergei V. Kalinin, Hong Li, Chad Risko, Jean-Luc Brédas, Alberto Salleo, C. Daniel Frisbie Feb 2016

Strain Effects On The Work Function Of An Organic Semiconductor, Yanfei Wu, Annabel R. Chew, Geoffrey A. Rojas, Gjergji Sini, Greg Haugstad, Alex Belianinov, Sergei V. Kalinin, Hong Li, Chad Risko, Jean-Luc Brédas, Alberto Salleo, C. Daniel Frisbie

Chemistry Faculty Publications

Establishing fundamental relationships between strain and work function (WF) in organic semiconductors is important not only for understanding electrical properties of organic thin films, which are subject to both intrinsic and extrinsic strains, but also for developing flexible electronic devices. Here we investigate tensile and compressive strain effects on the WF of rubrene single crystals. Mechanical strain induced by thermal expansion mismatch between the substrate and rubrene is quantified by X-ray diffraction. The corresponding WF change is measured by scanning Kelvin probe microscopy. The WF of rubrene increases (decreases) significantly with in-plane tensile (compressive) strain, which agrees qualitatively with density …

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Zncdmgse As A Materials Platform For Advanced Photonic Devices: Broadband Quantum Cascade Detectors And Green Semiconductor Disk Lasers, Joel De Jesus Feb 2016

Zncdmgse As A Materials Platform For Advanced Photonic Devices: Broadband Quantum Cascade Detectors And Green Semiconductor Disk Lasers, Joel De Jesus

Dissertations, Theses, and Capstone Projects

The ZnCdMgSe family of II-VI materials has unique and promising characteristics that may be useful in practical applications. For example they can be grown lattice matched to InP substrates with lattice matched bandgaps that span from 2.1 to 3.5 eV, they can be successfully doped n-type, have a large conduction band offset (CBO) with no intervalley scattering present when strained, they have lower average phonon energies, and the InP lattice constant lies in the middle of the ZnSe and CdSe binaries compounds giving room to experiment with tensile and compressive stress. However they have not been studied in detail for …

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System And Method For Identifying Electrical Properties Of Integrate Circuits, Mary Y. Lanzerotti Jan 2016

System And Method For Identifying Electrical Properties Of Integrate Circuits, Mary Y. Lanzerotti

AFIT Patents

A new method for displaying electrical properties for integrated circuit (IC) layout designs provides for improved human visualization of those properties and comparison of as designed layout design parameters to as specified layout design parameters and to as manufactured layout parameters. The method starts with a circuitry as designed layout in a first digital format, extracts values for electrical properties from that circuitry as designed layout then annotates those values back into the first digital format. The annotated circuitry as designed layout is then converted from the first digital format to a second digital format that can be converted to …

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Electron Beam Induced Deposition Of Highly Conductive Copper Nanowires From Bulk Liquids, Amjad M. Syam Jan 2016

Electron Beam Induced Deposition Of Highly Conductive Copper Nanowires From Bulk Liquids, Amjad M. Syam

Theses and Dissertations--Electrical and Computer Engineering

Electron-beam induced deposition (EBID) is a position-controlled technique that can directly fabricate nanometer-sized structures in functional materials. In the standard process, a gaseous precursor delivers the desired substance to the substrate for deposition. However, the material purity from these precursors is typically poor, which often negatively affects the functional properties of the deposit. Recently, bulk liquid precursors have been investigated as promising reactants for high purity deposition without the need for post-processing. In this work, EBID from bulk liquids is shown to yield highly conductive nanowire deposits. Aqueous solutions containing copper sulfate (CuSO4) and sulfuric acid (H2 …

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The Dawn Of New Quantum Dots: Synthesis And Characterization Of Ge1-Xsnx Nanocrystals For Tunable Bandgaps., Richard J. Esteves Jan 2016

The Dawn Of New Quantum Dots: Synthesis And Characterization Of Ge1-Xsnx Nanocrystals For Tunable Bandgaps., Richard J. Esteves

Theses and Dissertations

Ge1-xSnx alloys are among a small class of benign semiconductors with composition tunable bandgaps in the near-infrared spectrum. As the amount of Sn is increased the band energy decreases and a transition from indirect to direct band structure occurs. Hence, they are prime candidates for fabrication of Si-compatible electronic and photonic devices, field effect transistors, and novel charge storage device applications. Success has been achieved with the growth of Ge1-xSnx thin film alloys with Sn compositions up to 34%. However, the synthesis of nanocrystalline alloys has proven difficult due to larger discrepancies (~14%) in …

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Uv Light-Induced Aggregation Of Titania Submicron Particles, Can Zhou, Yashar Bashirzadeh, Timothy A. Bernadowsky Jr., Xiaoyu Zhang Jan 2016

Uv Light-Induced Aggregation Of Titania Submicron Particles, Can Zhou, Yashar Bashirzadeh, Timothy A. Bernadowsky Jr., Xiaoyu Zhang

Mechanical & Aerospace Engineering Faculty Publications

In this study, aggregation of TiO2 (rutile and anatase) submicron particles in deionized (DI) water under ultra-violet (UV) light irradiation was investigated. While no aggregation was observed in the dark, rutile and anatase submicron particles started aggregating upon application of UV light and ceased aggregation in about 2 and 8.4 h, respectively. It has been demonstrated that UV light directly mitigated the particle mobility of TiO2, resulting in a neutralization effect of the Zeta potential. It was also observed that rutile particles aggregated much faster than anatase particles under UV radiation, indicating that the Zeta potential of …

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Nanosphere Lithography And Its Application In Rapid And Economic Fabrication Of Plasmonic Hydrogenated Amorphous Silicon Photovoltaic Devices, Chenlong Zhang Jan 2016

Nanosphere Lithography And Its Application In Rapid And Economic Fabrication Of Plasmonic Hydrogenated Amorphous Silicon Photovoltaic Devices, Chenlong Zhang

Dissertations, Master's Theses and Master's Reports

Solar photovoltaic (PV) devices harvest energy from solar radiation and convert it to electricity. PV technologies, as an alternative to traditional fossil fuels, use clean and renewable energy while minimizing pollution. For decades researchers have been developing thin film solar cells as an important alternatives to the relatively expensive bulk crystal solar cell technology. Among those, hydrogenated amorphous silicon (a-Si:H) solar cells prevails for good efficiency, non-toxic and materially abundant nature. However, a-Si:H thickness must be minimized to prevent light induced degradation, so optical enhancement is necessary. Light manipulation has to be applied and carefully engineered to trap light within …

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Increasing Solar Energy Conversion Efficiency In Hydrogenated Amorphous Silicon Photovoltaic Devices With Plasmonic Perfect Meta – Absorbers, Jephias Gwamuri Jan 2016

Increasing Solar Energy Conversion Efficiency In Hydrogenated Amorphous Silicon Photovoltaic Devices With Plasmonic Perfect Meta – Absorbers, Jephias Gwamuri

Dissertations, Master's Theses and Master's Reports

Solar photovoltaic (PV) devices are an established, technically-viable and sustainable solution to society’s energy needs, however, in order to reach mass deployment at the terawatt scale, further decreases in the levelized cost of electricity from solar are needed. This can be accomplished with thin-film PV technologies by increasing the conversion efficiency using sophisticated light management methods. This ensures absorption of the entire solar spectrum, while reducing semiconductor absorber layer thicknesses, which reduces deposition time, material use, embodied energy and greenhouse gas emissions, and economic costs. Recent advances in optics, particularly in plasmonics and nanophotonics provide new theoretical methods to improve …

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Biolabeling Through The Use Of Water-Soluble Colloidal Quantum Dots, Cody Stombaugh Jan 2016

Biolabeling Through The Use Of Water-Soluble Colloidal Quantum Dots, Cody Stombaugh

Honors Projects

Nanomaterials continues to be a growing field of study due to their wide range of potential applications. Quantum dots are artificially synthesized crystalline clusters of atoms able to confine electron motion as a result of their incredibly small size. Recently, medical applications of nanomaterials have expanded greatly. Quantum dots are ideal for biolabeling due to their rather narrow photoluminescence emission peaks. By synthesizing quantum dots of a specific diameter, it is possible to predetermine the peak photoluminescence wavelength of a sample. Through ligand exchange and immunoconjugation of the quantum dots with proteins, it is possible to use the quantum dots …

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Improving The Capacity, Durability And Stability Of Lithium-Ion Batteries By Interphase Engineering, Qinglin Zhang Jan 2016

Improving The Capacity, Durability And Stability Of Lithium-Ion Batteries By Interphase Engineering, Qinglin Zhang

Theses and Dissertations--Chemical and Materials Engineering

This dissertation is focus on the study of solid-electrolyte interphases (SEIs) on advanced lithium ion battery (LIB) anodes. The purposes of this dissertation are to a) develop a methodology to study the properties of SEIs; and b) provide guidelines for designing engineered SEIs. The general knowledge gained through this research will be beneficial for the entire battery research community.

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Synthesis Of Titania Thin Films With Controlled Mesopore Orientation: Nanostructure For Energy Conversion And Storage, Suraj R. Nagpure Jan 2016

Synthesis Of Titania Thin Films With Controlled Mesopore Orientation: Nanostructure For Energy Conversion And Storage, Suraj R. Nagpure

Theses and Dissertations--Chemical and Materials Engineering

This dissertation addresses the synthesis mechanism of mesoporous titania thin films with 2D Hexagonal Close Packed (HCP) cylindrical nanopores by an evaporation-induced self-assembly (EISA) method with Pluronic surfactants P123 and F127 as structure directing agents, and their applications in photovoltaics and lithium ion batteries. To provide orthogonal alignment of the pores, surface modification of substrates with crosslinked surfactant has been used to provide a chemically neutral surface. GISAXS studies show not only that aging at 4°C facilitates ordered mesostructure development, but also that aging at this temperature helps to provide orthogonal orientation of the cylindrical micelles which assemble into an …

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Overview Of Fiber Optic Sensor Technologies For Strain/Temperature Sensing Applications In Composite Materials, Manjusha Ramakrishnan, Ginu Rajan, Yuliya Semenova, Gerald Farrell Jan 2016

Overview Of Fiber Optic Sensor Technologies For Strain/Temperature Sensing Applications In Composite Materials, Manjusha Ramakrishnan, Ginu Rajan, Yuliya Semenova, Gerald Farrell

Articles

This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements.

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Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian Jan 2016

Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian

Theses and Dissertations

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that …

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