lnAs/Ga_(1-x) ln_xSb strained-layer superlattices grown by molecular-beam epitaxy

We report the successful growth of InAs/Ga_(1−x)In_xSb strained‐layer superlattices by molecular‐beam 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 As‐background pressure. Best strained‐layer superlattice structural quality is achieved for samples grown at fairly low substrate temperatures (<400 °C). 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 Å, InAs/Ga_(0.75)In_(0.25)Sb superlattice, demonstrating that far‐infrared cutoff wavelengths are compatible with short superlattice periods in this material system.