Interband Cascade Infrared Photodetectors with InAs/GaSb superlattice absorbers

摘要

We present a study of the temperature-dependence of the performance metrics of a set of five GaSb-based MWIR interband cascade infrared photodetectors employing InAs/GaSb superlattice absorbers. The cutoff wavelengths of the detectors varied from 4.3 μm at 78 K to 5.1 μm at 300 K. In this study, the number of stages and absorber thicknesses were varied between the samples. Two of the samples were single-stage devices with long (> 1.0 μm) absorbers, while the other three were multiple-stage detectors with short (< 1.0 μm) absorbers. The detectors were designed so that the incoming signal was traveling in the same direction as the flow of the photo-excited electrons. We experimentally show that multiple-stage detectors with shorter absorbers are able to achieve higher values of R_oA and are have a photoresponse that is less sensitive to temperature. This confirms their potential utility for high-temperature detector operation. For the particular samples in this study, the multiple-stage devices were able to achieve better sensitivities above 250 K than the single-stage samples. It is notable that for most of the samples, a fit of the temperaturedependence of the dark current yielded an activation energy slightly larger than half the zero-temperature bandgap. This suggests that there may be an electric field and depletion region in the absorber and the interband transport in this series of detectors is governed by generation-recombination current, even at high temperature. Also, preliminary results of interband cascade infrared photodetectors at longer wavelengths (>12 μm) are reported.