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Title:Material processing of quantum well infrared photodetectors
Author(s):Malin, Jay Ira
Doctoral Committee Chair(s):Hsieh, Kuang-Chien
Department / Program:Electrical and Computer Engineering
Discipline:Electrical and Computer Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Electronics and Electrical
Physics, Condensed Matter
Physics, Optics
Abstract:The material and device characterization of furnace and rapid thermally annealed (RTA) GaAs/AlGaAs multiple quantum well (MQW) infrared (IR) photodetectors (QWIPs) epitaxially grown on GaAs and Si substrates is presented. The advances in epitaxial growth allow the precise control of the dimensions, doping, and matrix concentration of the MQW. Therefore, the design of a QWIP with particular electrical and optical characteristics may be undertaken. To utilize a post-growth anneal to improve the QWIP's performance, the trade-offs must be considered to determine its usefulness. Depending on the application, the anneal may be deemed unnecessary due to its detrimental effect on a particular aspect of the operation.
The availability of high quality GaAs and Si substrates, complemented by the maturity of GaAs device processing techniques, makes the QWIP an ideal candidate for 8-14 $\mu$m long wavelength infrared (LWIR) detection. An extensive exploration of the interdiffusion process leads to the development of a suitable technique for shifting the optical response without harming the electrical characteristics. This, however, is a difficult task in light of the out-diffusion of the dopant from the wells into the barriers, which results in a high dark current.
Reading-out the QWIP focal plane array (FPA) (on GaAs substrate) is accomplished by indium bump-bonding the FPA to a Si multiplexer. Thermal cycling the hybrid, unfortunately, results in destroyed bonds due to the difference in thermal expansion coefficient of the two substrates. Growing the QWIP on a Si substrate better satisfies the packaging requirements; however, the dark current is higher. The technique of annealing for the purpose of defect annihilation results in improvements in the absolute response and a reduction in the dark current.
Issue Date:1995
Rights Information:Copyright 1995 Malin, Jay Ira
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9543666
OCLC Identifier:(UMI)AAI9543666

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