Section II, A, 1 (ARO), 4.3 Identification of Surface Defect Candidates and their passivation in Strained- Layer Type-II Superlattices for Infrared Detectors
Abstract
Technical problem: The InAs/GaSb and InAs/InAsSb type-Il strain-layer superlattices (T2SLS) are of great importance and promise for mid-wave and long-wave infrared (IR) detectors for a variety of civil and military applications. While the T2SL approaching the empirical Rule-07 benchmark of bulk mercury cadmium telluride s (MCT) performance level, the dark-cun T2SLS remains significantly higher than that of bulk MCT detectors. One of the major origins of dark current in detectors band gap semiconductors is the surface current associated with surface states in the junction due to the dangling chemical be semiconductor surface. One approach to mitigate these currents is surface passivation via foreign atoms (for example chalcogenides as sulfur or selenium) which in tum change the electronic structure of the semiconductor surface. Proposed Effort: The objective of the proposed research is to carry out ab initio electronic structure calculations to: (1) Identify surface defects and dopant atoms on InAs, GaSb, and InSb (001) surfaces; (2) Study the effect of strain on formation energies transition levels, and surface states of neutral and charged surface defects; and (3) Understand the interactions between different defects and/or dopant atoms in order to optimize the passivation of the surface to mitigate the surface defects. The ab initio calculations will elucidate the underlying ofigin of the atomic-scale properties which will lead to models of the physical mechanisms governing the (1) formation of surface defect complexes, (2) the compensation of dopant atoms, (3) the pinning of the Fermi-level, and the (4) surface defects. We will consider a number of defects on the InAs, InSb, and InAsSb (001) surfaces including, (1) In, As or As or Sb vacancy; (2) Asor Sb antisites (ASIn), and (3) In, As, and Sb interstitials. Compared with defect in bulk materials, the formation properties of defects on the surfaces of T2SLS can be affected by many alternative structure features, including strain, surfaces or interfaces, and the local chemical environment. The studies will also investigate the structural and electronic properties of sulfur-passivated InAs and InSb (001) exhibiting a number of different reconstructions. Significance of work/relevance to US Army applications: The proposed work will identify those surface defects which have on dark currents, predict dopants which will eliminate their occurrence and hence allow mitigation strategies to improve the performance. Impact on Education: The proposed research will expand and strengthen the research and educational activities of the W. M. Keck Computational Materials Theory Center at California State University Northridge, a Hispanic-serving institution. The objective of the educational activities is to continue fostering frontier research/education experience in multidisciplinary computational materials science to students from underrepresented groups to achieve national competitiveness.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510066
Entities
People
- Nicholas Kioussis
Organizations
- Army Contracting Command
- California State University, Northridge
- United States Army