Measurement of InAsSb bandgap energy and InAs/InAsSb band edge positions using spectroscopic ellipsometry and photoluminescence spectroscopy

Authors

P. T. Webster, Arizona State University
N. A. Riordan, Arizona State University
S. Liu, Arizona State University
E. H. Steenbergen, U. S. Air Force Research Laboratory, AFRL/RXAN, Wright Patterson, Ohio
R. A. Synowicki, J. A. Woollam Co., Inc., 645 M. Street, Suite 102, Lincoln, Nebraska
Y.-H. Zhang, Arizona State University
S R. Johnson, Arizona State University at the Tempe CampusFollow

Document Type

Article

Date of this Version

2015

Citation

JOURNAL OF APPLIED PHYSICS 118, 245706 (2015)

Comments

U.S. Government Work

Abstract

The structural and optical properties of lattice-matched InAs_0.911Sb_0.089 bulk layers and strainbalanced InAs/InAs_1-xSb_x (x~0.1–0.4) superlattices grown on (100)-oriented GaSb substrates by molecular beam epitaxy are examined using X-ray diffraction, spectroscopic ellipsometry, and temperature dependent photoluminescence spectroscopy. The photoluminescence and ellipsometry measurements determine the ground state bandgap energy and the X-ray diffraction measurements determine the layer thickness and mole fraction of the structures studied. Detailed modeling of the X-ray diffraction data is employed to quantify unintentional incorporation of approximately 1% Sb into the InAs layers of the superlattices. A Kronig-Penney model of the superlattice miniband structure is used to analyze the valence band offset between InAs and InAsSb, and hence the InAsSb band edge positions at each mole fraction. The resulting composition dependence of the bandgap energy and band edge positions of InAsSb are described using the bandgap bowing model; the respective low and room temperature bowing parameters for bulk InAsSb are 938 and 750 meV for the bandgap, 558 and 383 meV for the conduction band, and -380 and -367 meV for the valence band.