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Title:Defect characterization of antimonide-based type-II superlattices for infrared detection
Author(s):Zuo, Daniel Yuan
Director of Research:Wasserman, Daniel
Doctoral Committee Chair(s):Wasserman, Daniel
Doctoral Committee Member(s):Bayram, Can; Jin, Jianming; Shaner, Eric A
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Infrared (IR)
Electron Beam Induced Current (EBIC)
Time-resolved Photoluminescence (TRPL)
Abstract:Type II superlattices (T2SLs) have undergone a significant amount of development and progress since their initial proposed use for the detection of mid- to long-wavelength infrared (MWIR, LWIR) radiation. The type-II broken band gap alignment of these heterostructures allows electrons and holes to be confined in separate but adjacent, nanometer scale thickness, material layers. When arranged in a highly periodic structure comprised of thin layers of alternating materials, known as a superlattice (SL), the carriers form minibands that have an effective band gap lower than that of the constituent materials and suited for MWIR and LWIR applications. Traditionally, InAs/GaSb has been the preferred material system for T2SL IR detectors, but recent work has also explored the use of InAs/InAsSb as well. This thesis explores the characterization of carrier transport properties in T2SL devices through a variety of techniques, though primarily with the application of electron beam induced current (EBIC) measurements. For these EBIC measurements, using first-principle analysis of the low-injection diffusion of carriers generated by inelastic scattering of high-energy electrons, we develop theoretical models to characterize minority carrier diffusion length and surface recombination velocity in photodetectors along the growth direction. When applied to photodiodes with strain management layers incorporated in the InAs/GaSb SL, we used EBIC results to directly observe the improvement in carrier diffusion length and lifetime due to strain management. Furthermore, novel EBIC analysis of an nBn photodetector with InAs/InAsSb regions combined with lifetime measurements through time-resolved photoluminescence (TRPL) were demonstrated, forming a comprehensive characterization of the vertical transport qualities, including mobility and diffusivity. Additionally, we propose a sample design incorporating a T2SL in a bulk p-n diode for the application of deep level transient spectroscopy (DLTS) to measure defect energy levels within the SL band gap. Contained in this work are our initial results in testing our first sample designs. Defects specific to the T2SL have yet to be observed, but we were able to measure shallow states in bulk GaSb.
Issue Date:2015-11-18
Rights Information:Copyright 2015 Daniel Zuo
Date Available in IDEALS:2016-03-02
Date Deposited:2015-12

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