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Semiconductor and Optical Materials Commons™
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- Photoluminescence (2)
- Semiconductor switches (2)
- Diamond thin films (1)
- Directional couplers--Design and construction (1)
- Doped semiconductors (1)
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- Praseodymium (1)
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- VHDL (Computer hardware description language) (1)
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Articles 1 - 13 of 13
Full-Text Articles in Semiconductor and Optical Materials
Total Ionizing Dose Effects In Mosfet Devices At 77 K, Kevin J. Daul
Total Ionizing Dose Effects In Mosfet Devices At 77 K, Kevin J. Daul
Theses and Dissertations
Total ionizing dose effects on thermal oxide and reoxidized nitrided oxide (RNO) MOSFET devices at 77 K were studied. The MOSFETs were immersed in liquid nitrogen and irradiated, using a 60Co source, up to 1 Mrad(Si) at a dose rate of 107 rads(Si)-sec. Drain current-gate voltage characteristics were obtained and used to determine threshold voltage and transconductance. At 77 K the subthreshold slopes indicated no observed buildup of interface states in any of the transistors. Furthermore, all transistors experienced very little change in the transconductance. Typical negative shifts in threshold voltage as dose increased were observed in all of …
Model Of A Single Impurity In A Wide Bandgap Semiconductor Describing Electric Field Screening, Anthony N. Dills
Model Of A Single Impurity In A Wide Bandgap Semiconductor Describing Electric Field Screening, Anthony N. Dills
Theses and Dissertations
A mathematical model of the influence on electric field screening arising from a single impurity in a wide bandgap semiconductor has been numerically investigated and compared with analytically derived solutions. The parameter set chosen to perform the comparison of analytical solution and numerical solution is based upon a bismuth silicate crystal. Both the analytical calculations and the numerical calculations are an attempt to mathematically model the internal electric field within a semiconductor. Two types of impurities were looked at: a single donor level and a single trap impurity level. In general, after an abrupt application of a voltage across the …
Photoluminescence Spectroscopy Of 4h- And 6h-Sic, William A. Davis
Photoluminescence Spectroscopy Of 4h- And 6h-Sic, William A. Davis
Theses and Dissertations
Typical undoped bulk grown SiC shows n- or p-type conductivity due to residual impurities such as nitrogen, boron, or aluminum. In order to produce high resistivity material, vanadium can be used as a compensating dopant. Since vanadium is an amphoteric dopant in SiC, it produces either a donor state, VSi4+(3d1) → VSi5+(3d0), or an acceptor state, VSi4+(3d1) → VSi3+(3d2). Thus, vanadium doping can compensate both n- and p-type conductivity. In this work, vanadium doped and undoped 4H- and 6H-SiC grown …
Design, Fabrication, Modeling, And Optical Characterization Of Organic Polymer Nonlinear Directional Couplers, John N. Berry
Design, Fabrication, Modeling, And Optical Characterization Of Organic Polymer Nonlinear Directional Couplers, John N. Berry
Theses and Dissertations
This research was an investigation into the suitability of a recently developed polymer, polyphenylene, as a material for integrated optical circuits (IOCs). Polymers show great promise in the area of IOCs because of material processing advantages, compatibility with most existing integrated circuit technology, and relatively strong nonlinear optical characteristics. This thesis contains an overview of: dielectric waveguides, linear and nonlinear directional coupler theory; various models useful in the design and analysis of optical waveguides; the fabrication of three different waveguide designs; the experimental apparatus and procedure used to optically characterize the waveguides; and the experimental results of the characterization. Waveguiding …
The Junction Characteristics And Current Conduction Mechanisms Of Gainp2 N+P Diodes And Solar Cells, Kitt C. Reinhardt
The Junction Characteristics And Current Conduction Mechanisms Of Gainp2 N+P Diodes And Solar Cells, Kitt C. Reinhardt
Theses and Dissertations
This work involves an investigation of GaInP2 n+p diode and solar cell dark current mechanisms, the defect centers that affect these mechanisms, and the response of dark current and solar cell photovoltaic parameters to I MeV electron irradiation and thermal annealing. Dark current due to carrier diffusion, recombination, and tunneling were identified, and recombination current was found to dominate at the maximum power-point voltage of the GaInP2 solar cells. Carrier recombination was found to occur via defect centers at the perimeter and within the bulk of the junction. Two deep majority-hole trap centers were found at E …
The Current Voltage Characteristics Of Electron Beam Controlled Thin Film Diamond Switches, Christopher Anthony Molina
The Current Voltage Characteristics Of Electron Beam Controlled Thin Film Diamond Switches, Christopher Anthony Molina
Electrical & Computer Engineering Theses & Dissertations
The dark current of natural diamond thin films and the induced current due to electron-beam irradiation was measured up to a range of 7000Ncm'. The contact material was aluminum, annealed and unannealed. Switching experiments were performed with electron energies ranging from 70keV to 172keV. The switching results obtained are strongly dependent on the biasing polarity, incident electron energy, and whether the contact is blocking or Ohmic in nature. A simple model which takes traps into consideration allows us to explain the various switching responses. The range of electrons which define, in part, the switch mode was measured for one sample …
Transient Simulations And Modelling Of Semi-Insulating Gaas Photoconductive Switches, Prasun Kumar Raha
Transient Simulations And Modelling Of Semi-Insulating Gaas Photoconductive Switches, Prasun Kumar Raha
Electrical & Computer Engineering Theses & Dissertations
The primary objective of this thesis is to develop a one-dimensional transient simulator for Photoconductive Semiconductor Switches (PCSS) taking into consideration the material characteristics, the internal physical effects, and the external circuit. Simulations have been performed to study the device behavior at different voltage levels for copper-doped silicon-compensated GaAs material, though other materials could easily be simulated by changing the parameters. The model includes hole transport, and the results demonstrate the effect of hole injection, with and without recombination centers. In addition to developing a one-dimensional transient simulator, the role of various physical effects, such as the field-dependence of trapping …
The Excitation Mechanism Of Praseodymium-Doped Semiconductors, Paul L. Thee
The Excitation Mechanism Of Praseodymium-Doped Semiconductors, Paul L. Thee
Theses and Dissertations
This study on praseodymium Pr luminescence in AlxGa1-xAs was conducted to enhance the understanding of the excitation mechanism. Pr was implanted at 390 keV with doses from 5 x 1012 to 5 x 1013 sq cm into AlxGa1-xAs x0.0 to 0.50 wafers which were annealed using the rapid thermal annealing RTA method. Low temperature photoluminescence PL was conducted using an Ar-ion laser and Ge detector. PL emissions of Pr from all hosts include peaks near 1.3 and 1.6 µm which are assigned to the intra-4f transitions of 1G4 yielding 3H5 …
Rapid And Accurate Timing Simulation Of Radiation-Hardened Digital Microelectronics Using Vhdl, Charles P. Brothers Jr.
Rapid And Accurate Timing Simulation Of Radiation-Hardened Digital Microelectronics Using Vhdl, Charles P. Brothers Jr.
Theses and Dissertations
This dissertation presents the development of a fast, accurate, timing simulation capability based on VHSIC Hardware Description Language VHDL without the use of back annotation of timing delay information. This VHDL-based timing simulator is intended for use with radiation-hardened microelectronics in simulating timing of circuit operation in pre-radiation, post-radiation 1 MradSi total dose, and ionizing dose radiation environments. Development of the timing models are presented. The implementation of the timing models are incorporated into a VHDL library composed of basic logic gates and flip-flops. Simulations of complex circuits were run in SPICE and VHDL to assess the timing accuracy and …
Solid State Nmr Of Hydrogen In Thin Film Synthetic Diamond, G. Burnside, Roger M. Hawk, Richard A. Komoroski, W. D. Brown
Solid State Nmr Of Hydrogen In Thin Film Synthetic Diamond, G. Burnside, Roger M. Hawk, Richard A. Komoroski, W. D. Brown
Journal of the Arkansas Academy of Science
Thin film synthetic diamond promises to be the next semiconductor material, if the manufacturing processes which produce it can be controlled. Solid state nuclear magnetic resonance (NMR) using magic angle spinning (MAS) is used to measure the content of hydrogen in diamond which controls the resistivity of the diamond thin films. Spectral results are presented for proton NMR of thin film synthetic diamond. Experimental calibration techniques using BaF2 as the hydrogen standard will be discussed, as well as acquisition times, pulsing sequences, spinning rates, and rotor composition.
Reaction Of Titanocene Dichloride With Acetylenedicarboxylate, Tanya L. Hagler, Mark Draganjac, Paul M. Nave, J. Ed Bennett, Farooq Kahn, Robert Engelken, Gerard Williams, Chris Poole, Kwok Fai Yu
Reaction Of Titanocene Dichloride With Acetylenedicarboxylate, Tanya L. Hagler, Mark Draganjac, Paul M. Nave, J. Ed Bennett, Farooq Kahn, Robert Engelken, Gerard Williams, Chris Poole, Kwok Fai Yu
Journal of the Arkansas Academy of Science
The reaction of Cp2TiCl2 with either the mono- or dipotassium salt of acetylenedicarboxylic acid (ADC) gives high yields of an insoluble orange product. The insoluble compound shows potential semiconductor behavior, as evidenced by an apparent bandgap in the orange region of the visible spectrum. Under N2 ,the compound decomposes at 238° C, eventually losing approximately 46% total mass up to 1350° C. The exothermic decomposition in air, beginning at 235° C, results in the formation of titanium oxides.
Tetraethylene Gycol-Based Electrolytes For High Temperature Electrodeposition Of Compound Semiconductors, Chris Poole, Robert Engelken, Brandon Kemp, Jason Brannen
Tetraethylene Gycol-Based Electrolytes For High Temperature Electrodeposition Of Compound Semiconductors, Chris Poole, Robert Engelken, Brandon Kemp, Jason Brannen
Journal of the Arkansas Academy of Science
We report an investigation of tetraethylene glycol (TEG) solutions of chloride salts (CdCl2 ,TeCl4 ,and HgCl2 ) for electrodeposition of films of CdTe and Hg1.xCdxTe, leading II-VI semiconductors. The high boiling point (314°C), below-room temperature (T) (-6°C) melting point, adequate metal chloride solubilities, and low toxicity of TEG make it a good candidate for electrodeposition at T > 200°C. Such temperatures tend to activate growth of larger crystallites than with aqueous electrolytes at T< 100 °C, as are advantageous in optoelectronic applications. Initial results do, indeed, indicate a dramatic increase in crystallinity with deposition temperature, especially for the CdTe films which are nearly amorphous when grown at room temperature. Hg1.xCdxTe films (x< 0.5) are marginally polycrystalline when grown at room temperature but also improve in crystallinity at higher growth temperatures. There appears to be a strong decrease in film adherence and uniformity as growth temperature increases for both materials probably because the greatly increased carrier concentrations at higher temperatures increase film conductivity which, in turn, supports easy electroplating of protruding loose dendritic and/or columnar crystallites, instead of the monolayer-by monolayer growth of lower conductivity material as occurs at lower temperatures, especially in the higher bandgap/lower conductivity CdTe. The same increase in film conductivity with temperature is responsible for the decrease in the relative photosensitivity of both the CdTe and Hg1.x CdxTe with temperature. At all temperatures, the inferior adherence, uniformity, and photosensitivity as well as the superior crystallinity of Hg1.xCd xTe over that of the CdTe are also explained by its lower bandgap and higher conductivity. On balance, however, the initial results prove the utility of high temperature TEG electrolytes for electrodepositing CdTe and Hg1.xCdxTe films with much better crystallinity than for those grown at lower temperatures, notably in aqueous baths.
Evaluation Of Photodiode Arrays For Use In Rocket Plume Monitoring And Diagnostics, Dallas Snider, M. Keith Hudson, Robert B. Shanks, Reagan Cole
Evaluation Of Photodiode Arrays For Use In Rocket Plume Monitoring And Diagnostics, Dallas Snider, M. Keith Hudson, Robert B. Shanks, Reagan Cole
Journal of the Arkansas Academy of Science
The spectroscopic analysis of plume emissions is a non-intrusive method which has been used to check for fatigue and possible damage throughout the pumps and other mechanisms in a rocket motor or engine. These components are made of various alloys. Knowing the composition of the alloys and for which parts they are used, one can potentially determine from the emissions in the plume which component is failing. Currently, Optical Multichannel Analyzer systems are being used which utilize charge coupled devices, cost tens of thousands of dollars, are somewhat delicate, and usually require cooling. We have developed two rugged instruments using …