Long wavelength InAs/InAsSb superlattice barrier infrared detectors with p-type absorber quantum efficiency enhancement

We studied long and very long wavelength InAs/InAsSb superlattice barrier infrared detectors that contain p-type absorber layers in order to take advantage of the longer electron diffusion length for quantum efficiency (QE) enhancement. While they can achieve higher QE than devices that use only n-type absorbers, their dark current characteristics are affected by the presence of metallurgical and surface p-n junctions, and are best operated under lower biasing conditions where the tunneling dark currents are less pronounced. Rather than using a p-type absorber only, a barrier infrared detector structure with a combination of p- and n-type absorber sections can benefit from a shallower mesa etch that reduces fabrication demands and also decreases the p-type absorber exposed surface area. We compare four complementary barrier infrared detector structures that use an n-type absorber, a combination of p- and n-type absorbers, or a p-type absorber and briefly report results from a 13.3 mu m cutoff focal plane array.