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Fast Neutron Effects On Time Delay Occuring In Gallium Arsenide Laser Diodes., James Owen Schroeder

Electrical and Computer Engineering ETDs

A study has been made on the effects of fast neutron irradiation on time delay occurring in diffused GaAs laser diodes operating at 77° K and 300° K. Measurements were performed at 300° K prior to irradiation and thence after successive exposure to neutron irradiation to a maximum of about 1.2 x 10^14 nvt (>10 KeV). At 77° K, measurements were limited to a pre-irradiation characterization and a characterization after the final irradiation. A double acceptor model is used to account for the observed changes in the delay characteristics as a result of both temperature changes and neutron irradiation. …

An Experimental Study Of Ultrahigh Fluence Oxygen Ion Implantation In Silicon, Charles Burton Fite

Electrical and Computer Engineering ETDs

An investigation was made to determine the feasibility of using ultrahigh fluences of implanted oxygen ions to create a usable oxide layer on silicon for device applications. Previous studies have indicated that SiO₂ can indeed be formed in this manner, but very little work has been reported on the electrical and structural nature of the resulting oxide-silicon interface. Six implants with fluences ranging from 1.25 x 10¹⁷ to 1 x 10¹⁸ (O₂)⁺ /cm² were performed into p-type silicon wafers. The implanted material was then studied to determine how the variables of anneal time, …

Electrical Parameter Correlations For Radiation Hardness Assurance Of Operational Amplifiers, John L. Mullis

Electrical and Computer Engineering ETDs

In the manufacture of integrated circuits, a consider­able amount of attention is given to controlling fabrication processes. This is required if high production yield and consistent quality are to be obtained. In addition to moni­toring critical parameters which are influenced by variables in processing, the packaged circuits undergo a variety of tests to determine whether they meet the desired electrical and environmental quality specifications. The problem of quality assurance is accepted and treated as an essential part of the production cycle.

State Estimation In Discrete-Time Linear Systems With Quadratic Form Observers, James Parish Shipley Jr.

Electrical and Computer Engineering ETDs

The problem considered in this dissertation is that of estimating the state of a system with a linear plant equation but having a measurement function which is a quadratic form in the state. It is first demonstrated by constructive proof that the problem has a solution if the controls have large enough magnitude, and some requirements on the minimum size of the control are discussed.

Three algorithms for estimating the state are obtained, one using the technique of maximum likelihood, the other two utilizing a more general Bayesian approach. In addition, a first-order approximate conditional mean filter is included for …

Dosimetry For High Intensity, 2 Mev Radiation., Clifford Ledth Schroeder

Electrical and Computer Engineering ETDs

The purpose of this effort is to evaluate several types of dosimeters being used with the 2-MeV flash X-ray facilities at The University of New Mexico and the Air Force Weapons Laboratory (AFWL). The types include lithium fluoride and calcium fluoride thermaluminescent dosimeters (TLD's), thin foil calorimeters, p-i-n diodes, cobalt glass chips, and #25 purple Cinemoid. The evaluation includes a comparison of dose measurements, repeatability, and useful ranges. This report describes fundamental physical mechanisms by which photons and high energy electrons interact with matter, the physical mechanisms of different dosimeters, and techniques for using the dosimeters. The calcium fluoride TLD's …

The Effects Of Ionizing Radiation On Gallium Arsenide Phosphide Metal-Insulator-Semiconductor Structures, Gordon James Kuhlmann

Electrical and Computer Engineering ETDs

MIS capacitors were fabricated on n-type GaAs 0.5 p 0.5 using a thermally grown chromium-doped insulator and chromium gate electrode. The fabrication procedures which lead to stable devices are described. The nature of the composite insulator, as well as that of a disordered layer of GaAs 0.5 P 0.5 underneath the insulator are discussed and related to observed electrical characteristics.

Flatband voltages for the capacitors subsequent to device fabrication ranged from -2.5 to -5 volts, corresponding to surface charge densities of 3.1 x 10 11 cm-2 to 4.3 x 10 11 cm-2. Fast interface state densities at flatband varied from …