Infrared optical characterization of InAs/Ga1−xInxSb superlattices

Abstract

InAs/Ga1−xInxSb superlattices have been examined by photoluminescence, photoconductivity, and infrared optical transmission. Samples display clear photoconductive thresholds at energies in agreement with band gaps derived from photoluminescence. Far-infrared energy gaps (8–14 μm and beyond) are obtained for InAs/Ga0.75In0.25Sb superlattices with periods <75 Å, in good agreement with gaps calculated from a simple two-band model. An absorption coefficient of ∼2000 cm−1 at 10 μm is measured in a superlattice with an energy gap of 11.4 μm. The magnitude and shape of this absorption edge is comparable to that of bulk Hg1−xCdxTe, suggesting that infrared detectors based on InAs/Ga1−xInxSb superlattices may be competitive in the 8–14 μm range and beyond.