XBnn and XBpp infrared detectors

XBnn and XBpp barrier detectors grown from III-V materials on GaSb substrates have recently been shown to exhibit a low diffusion limited dark current and a high quantum efficiency. Two important examples are InAsSb/AlSbAs based XBnn devices with a cut-off wavelength of λC~4.1 μm, and InAs/GaSb Type II superlattice (T2SL) based XBpp devices, with λC~9.5 μm. The former exhibit background limited performance (BLIP) at F/3 up to ~175 K, which is a much higher temperature than observed in standard generation-recombination limited devices, such as InSb photodiodes operating in the same Mid Wave IR atmospheric window. The Long Wave IR (LWIR) T2SL XBpp device has a BLIP temperature of ~100 K at F/2. Using the k · p and optical transfer matrix methods, full spectral response curves of both detectors can be predicted from a basic knowledge of the layer thicknesses and doping. The spectral response curves of LWIR gallium free InAs/InAs1−xSbx barrier devices have also been simulated. These devices appear to have a lower quantum efficiency than the equivalent InAs/GaSb XBpp devices.