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

Journal Article · Mon Feb 09 00:00:00 EST 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4908255· OSTI ID:22412603

Webster, P. T.; Riordan, N. A.; Liu, S.; Zhang, Y. -H.; Steenbergen, E. H. ^[1]; Synowicki, R. A. ^[2]

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1. U.S. Air Force Research Laboratory, AFRL/RXAN, Wright Patterson, Ohio 45433 (United States)
2. J. A. Woollam Co., Inc., 645 M. Street, Suite 102, Lincoln, Nebraska 68508 (United States)

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.

• OSTI ID: 22412603
• Journal Information: Applied Physics Letters, Vol. 106, Issue 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

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