Short-period InAs∕GaSb type-II superlattices for mid-infrared detectors

Using a newly developed envelope function approximation model that includes interface effects, several InAs∕GaSb Type-II superlattices (SLs) were designed for the 4μm detection threshold. The present model predicts that a given threshold can be reached with a wide range of progressively thinner SL periods and these thinner designs hold a promise of higher mobilities and longer Auger lifetimes, thus higher detector operating temperatures. The proposed SL structures were grown by molecular-beam epitaxy with slow growth rates. As predicted, the band gaps of SLs determined by low-temperature photoluminescence remained constant around 330meV for the samples in the period range from 50.6to21.2Å.