Passivation of type II InAs/GaSb superlattice photodiodes

Abstract

Recently, excellent infrared detectors have been demonstrated using Type II InAs/GaSb superlattice materials sensitive at wavelengths from 3 μm to greater than 32 μm. These results indicate that Type II superlattice devices may challenge the preponderance of HgCdTe and other state-of-the-art infrared material systems. As such, surface passivation is becoming an increasingly important issue as progress is made towards the commercialization of Type II devices and focal plane array applications. This work focuses on initial attempts at surface passivation of Type II InAs/GaSb superlattice photodiodes using PECVD-grown thin layers of SiO 2. Our results indicate that silicon dioxide coatings deposited at various temperatures improve photodetector resistivity by several times. Furthermore, reverse-bias dark current has been reduced significantly in passivated devices.