Ideal performance of and defect-assisted carrier recombination in MWIR and LWIR InAs/InAsSb superlattice detectors

摘要

Detector-relevant material properties are calculated for mid-wavelength infrared and long-wavelength infrared InAs/InAsSb type-Ⅱ superlattices (T2SLs). The electronic structure, transport, optical and carrier recombination properties are calculated for a series of T2SLs with varying Sb content in the InAsSb layer, and strain balanced for growth on GaSb substrates. The electronic-structure calculations rely on a well-tested envelope-function formalism based on fourteen bulk bands that has been extensively tested for InAs/GaInSb superlattice detectors. Targeted cutoff wavelengths are 5.2 microns and 10 microns. As the Sb composition and the strain in the InAsSb layer is varied the conduction and valence band edges also shift, and the resulting effect of these shifts on the Shockley-Read-Hall recombination rates from defect states in the gap is presented. Anisotropy in the carrier masses can also reduce detector performance; we find that hole mass anisotropy can be moderate for high-performance InAs/InAsSb superlattices.