Fundamental Study of Defects and Their Reduction in Type-II Superlattice Materials
Technical Report,01 Nov 2010,31 Oct 2017
University of Illinois - Urbana - Champaign Champaign United States
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GaSb-based Type-II superlattices T2SLs offer advantages for MWIR and LWIR detector applications due to their broad bandgap tunability, material uniformity, and predicted superior performance compared to traditional MCT HgCdTe IR photodetectors, which is mainly due to the suppressed Auger recombination in T2SLs through band-structure engineering. However, this predicted high performance has yet to be realized as T2SL IR detectors are still limited by defects and interface-related traps. A thorough understanding of detector theory, materials growth processes, and defect physics is crucial for suppression of defect formation and their adverse effects. Our team will develop a more accurate theory for the fundamental limits of T2SL detectors and study the physical origin of the defects as well as their structural, electrical, and optical properties. Novel growth methods and new materials and T2SL designs will be tested and utilized to drastically reduce the defect density and to improve IR detector performance. Our main objectives are 1. Identify and understand the origin of various defects in superlattice materials through experimental studies coupled to theoretical calculations. Correlate defect properties with minority carrier lifetime and device performance as a function of operating temperature. 2. Examine novel MBE and MOCVD growth methods and passivation that eliminate or mitigate defects in InAsGaSb, InAsInGaSb, and InAsInAsSb T2SLs. 3. Fabricate and characterize T2SL structures and devices, and develop models for understanding the device physics.