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Title: Absorption properties of type-II InAs/InAsSb superlattices measured by spectroscopic ellipsometry

Strain-balanced InAs/InAsSb superlattices offer access to the mid- to long-wavelength infrared region with what is essentially a ternary material system at the GaSb lattice constant. The absorption coefficients of InAs/InAsSb superlattices grown by molecular beam epitaxy on (100)-oriented GaSb substrates are measured at room temperature over the 30 to 800 meV photon energy range using spectroscopic ellipsometry, and the miniband structure of each superlattice is calculated using a Kronig-Penney model. The InAs/InAsSb conduction band offset is used as a fitting parameter to align the calculated superlattice ground state transition energy to the measured absorption onset at room temperature and to the photoluminescence peak energy at low temperature. It is observed that the ground state absorption coefficient and transition strength are proportional to the square of the wavefunction overlap and the ground state absorption coefficient approaches a maximum value of around 5780 cm{sup −1} as the wavefunction overlap approaches 100%. The absorption analysis of these samples indicates that the optical joint density of states is weakly dependent on the period thickness and Sb content of the superlattice, and that wavefunction overlap is the principal design parameter in terms of obtaining strong absorption in these structures.
Authors:
; ; ; ;  [1] ;  [2] ;  [3]
  1. Center for Photonics Innovation and School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States)
  2. U.S. Air Force Research Laboratory, AFRL/RXAN, Wright Patterson, Ohio 45433 (United States)
  3. J. A. Woollam Co., Inc., 645 M. Street, Suite 102, Lincoln, Nebraska 68508 (United States)
Publication Date:
OSTI Identifier:
22412603
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; DENSITY OF STATES; ELLIPSOMETRY; GALLIUM ANTIMONIDES; GROUND STATES; INDIUM ARSENIDES; LATTICE PARAMETERS; MOLECULAR BEAM EPITAXY; PHOTOLUMINESCENCE; PHOTONS; STRAINS; SUBSTRATES; SUPERLATTICES; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; WAVE FUNCTIONS