High-detectivity (>1*10/sup 10/ cm square root Hz/W), InAsSb strained-layer superlattice, photovoltaic infrared detector

A high-detectivity infrared photodiode grown using molecular beam epitaxy (MBE) is discussed. It consisted of a p-'i'-n device embedded in an InAs/sub 0.15/Sb/sub 0.85//InSb strained-layer superlattice (SLS) with equal 150 AA-thick layers. The SLS was grown on top of a thick, composition-graded In/sub x/Ga/sub 1-x/Sb (x=1.0-0.9) strain-relief buffer on an InSb substrate. The p- and n-type dopants were Be and Se, respectively. The doping level in the 'i' region represents the background doping level in the MBE system. The surface passivated device exhibited detectivities >or=1*10/sup 10/ cm square root Hz/W at wavelengths >