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Full-Text Articles in Engineering

Growth Optimization And Characterization Of Gallium Indium Nitride Grown By Electron-Cyclotron-Resonance Plasma-Assisted Molecular-Beam Epitaxy , William O. Liners Jan 1995

Growth Optimization And Characterization Of Gallium Indium Nitride Grown By Electron-Cyclotron-Resonance Plasma-Assisted Molecular-Beam Epitaxy , William O. Liners

Retrospective Theses and Dissertations

The various alloys of gallium indium nitride (GaInN) form a technologically important semiconductor materials system, with potential uses in optoelectronic devices operating in the blue and blue-green region of the visible light spectrum. There has been little work reported on the growth of these materials, and this research addresses fundamental issues related to the epitaxial growth of the nitrides. Our first step in this project was to install an electron cyclotron resonance (ECR) apparatus into our molecular beam epitaxy system. This provided a source for atomic nitrogen needed to grow the nitride materials. We also put together a photoluminescence (PL ...


Low Temperature Epitaxial Silicon Growth Using Electron Cyclotron Resonance Plasma Deposition , Scott Jeffrey Deboer Jan 1995

Low Temperature Epitaxial Silicon Growth Using Electron Cyclotron Resonance Plasma Deposition , Scott Jeffrey Deboer

Retrospective Theses and Dissertations

The development of a process for the low temperature (<600° C) growth of epitaxial silicon is an important technological issue. Conventional growth processes involve temperatures in excess of 1000° C. At these temperatures autodoping and impurity redistribution limit the feature size achievable in VLSI fabrication. As the typical feature sizes move into the submicron region, new processes for epitaxial silicon deposition will be needed. Another application for a low temperature growth process is the fabrication of solar cells on inexpensive metallurgical grade silicon wafers. Impurity diffusion from the wafer during conventional epitaxial silicon growth limits the quality of the solar cells if expensive high purity wafers are not used. We have used electron cyclotron resonance (ECR) plasma deposition to grow high quality epitaxial silicon films on silicon wafers. This growth technique relies on the deposition of silicon from a highly energetic hydrogen and silane plasma. The presence of the hydrogen in the plasma provides reactive etching of the silicon surface during growth. This reduces the oxygen and carbon contamination in the film as well as increasing the number of available growth sites on the surface by displacing the adsorbed hydrogen. By optimizing the growth pressure, substrate temperature, microwave power, substrate bias and silane to hydrogen ratio we have developed a process which provides enhanced growth rates and good uniformity at temperatures (425-575° C) significantly below those used in conventional processes. The structural and electrical properties of the films have been characterized using SEM, TEM, Raman spectroscopy, UV reflectance, spreading resistance profiles, Hall mobility measurements, and both four-point probe and van der Pauw resistivity measurements.


Increasing The Efficiency Of A Piezoelectric Aluminum Nitride Microstrip Resonator By Utilizing High Temperature Superconductors , Edward David Goff Jan 1995

Increasing The Efficiency Of A Piezoelectric Aluminum Nitride Microstrip Resonator By Utilizing High Temperature Superconductors , Edward David Goff

Retrospective Theses and Dissertations

High temperature superconductors have potential applications in the field of microwave devices and circuits. To utilize these materials in such a way as to increase the efficiency of these microwave devices would be beneficial for high efficiency/low noise applications. This dissertation accomplishes the following goals: (1) The design and fabrication of an initial device that increases the quality factor, Q, and therefore the efficiency of a high frequency thin film resonator which uses superconducting metal as the device's electrode, (2) the measurement and characterization of this device, (3) the theoretical calculation and predicted performance of this device, and ...


Monolithic Finite Gain Amplifiers Employing Active Voltage Attenuators In The Feedback And A Charge Conserving Macromodel For Mosfets , Joon-Yub Kim Jan 1995

Monolithic Finite Gain Amplifiers Employing Active Voltage Attenuators In The Feedback And A Charge Conserving Macromodel For Mosfets , Joon-Yub Kim

Retrospective Theses and Dissertations

Two separate topics, both focused on analog and mixed signal monolithic circuit design, are presented. The first concentrates on the design of monolithic finite gain amplifiers employing active voltage attenuators in the feedback loop. Three MOS active voltage attenuators suitable for realizing finite gain amplifiers along with an operational amplifier are investigated. Monolithic single input amplifiers, two or more input summing/subtracting amplifiers, and differential amplifiers are readily attainable with this approach. The attenuators and amplifiers are theoretically analyzed, simulated on SPICE, and experimentally characterized in the laboratory. The performance of the attenuators and amplifiers is characterized with experiments by ...


Electronic And Photonic Devices: Experimental Investigations Of Hydrogenated Amorphous Silicon Substrate N+/I/P+ Solar Cell And Fundamental Properties Of Quantum Wells With Cylindrical Geometry And Applications To Electronics And Photonics , Er-Xuan Ping Jan 1995

Electronic And Photonic Devices: Experimental Investigations Of Hydrogenated Amorphous Silicon Substrate N+/I/P+ Solar Cell And Fundamental Properties Of Quantum Wells With Cylindrical Geometry And Applications To Electronics And Photonics , Er-Xuan Ping

Retrospective Theses and Dissertations

This thesis consists of two different parts: (I) experimental investigations of hydrogenated amorphous silicon substrate n[superscript]+/i/p[superscript]+ solar cells and, (II) fundamental properties of quantum wells with cylindrical geometry and applications to electronics and photonics;Part I. The substrate structural n[superscript]+/i/p[superscript]+ solar cells based on a-Si:H materials are fabricated by a radio frequency (RF) triode geometric plasma enhanced chemical vapor deposition (PECVD) system. The solar cells have been electrically and optically tested. Two different substrates, tin-oxide coated glass and stainless steel foil, are used. An RF magnetron sputtering system is used to ...