The effect of p-doping in mid- and long-wavelength InAs/InAsSb superlattice complementary barrier infrared detectors

We compare mid-wavelength InAs/InAsSb superlattice complementary barrier infrared detectors (CBIRDs) with n-type and p-type absorbers and also report results on a series of five long-wavelength CBIRD samples that have the same structure but with a systematic variation in the absorber doping profile. Our studies show that devices containing p-type absorber layers can take advantage of the longer electron diffusion length for enhanced quantum efficiency (QE) compared to those that use only n-type absorbers, while the dark current performance is better for devices that use only n-type absorbers. Under typical operating conditions, the use of p-type absorbers manifests in higher bulk and surface generation-recombination (G-R) dark current in mid-wavelength detectors and in higher trap-assisted tunneling dark current in long-wavelength detectors. The QE/dark current trade-off is observed in both mid- and long-wavelength detectors, but it is less pronounced in the mid-wavelength devices.