lnAs/Ga1 _x lnxSb strained-layer superlattices grown by molecular-beam epitaxy

We report the successful growth oflnAs/Ga 1 _ x Inx Sb strained-layer superlattices by molecularbeam epitaxy. The superlattices are grown on thick, strain-relaxed InAs or GaSb buffer layers on ( 100)-oriented GaAs substrates. A short-period, heavily strained superlattice at the GaAs interface is found to improve the structural quality of the buffer layer. Arsenic incorporation in nominally pure GaSb layers is found to depend strongly on substrate temperature and Asbackground pressure. Best strained-layer superlattice structural quality is achieved for samples grown at fairly low substrate temperatures ( < 400 oc). Photoluminescence measurements indicate that the energy gaps of the strained-layer superlattices are smaller than those of InAs/GaSb superlattices with the same layer thicknesses, in agreement with the theoretical predictions of Smith and Mailhiot [J. Appl. Phys. 62, 2545 (1987) ]. Far-infrared photoluminescence is observed from a 37/25 A, InAs/Gao_75 In0 _25 Sb superlattice, demonstrating that far-infrared cutoff wavelengths are compatible with short super lattice periods in this material system.