GROWTH AND CHARACTERIZATION OF INAS/GA1-XINXSB STRAINED-LAYER SUPERLATTICES

We report the successful growth of InAs/Ga1-xInxSb strained-layer superlattices, which have been proposed for far-infrared applications. The samples were grown by molecular beam epitaxy, and characterized by reflection high-energy electron diffraction, x-ray diffraction, and photoluminescence. Best structural quality is achieved for superlattices grown on thick, strain-relaxed, GaSb buffer layers on GaAs substrates 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)]. In the case of a 37 Å/25 Å, InAs/Ga 0.75In0.25Sb superlattice, an energy gap of 140±40 meV (≊9 μm) is measured. This result demonstrates that far-infrared cutoff wavelengths are compatible with short superlattice periods in this material system.