Reduction of surface leakage current of InAs/GaSb long-wavelength superlattice detectors using SiO2 and anodic sulfide composite passivation

We investigate two passivation methods for long-wavelength infrared type-II InAs/GaSb superlattice (T2SL) photodiodes with the PπBN structure containing an InAs/AlSb hole barrier layer. In order to eliminate the surface defects of T2SL better to further reduce the surface dark current, anodic vulcanization and SiO2 composite passivation method is adopted to optimize the original SiO2 passivation method. At 77 K, the I–V curve of the devices under the two passivation methods are obtained. Compared with passivation-only SiO2, the dark current density of the anode sulfide and SiO2 composite passivation detector is reduced by one order of magnitude, and the surface resistivity is effectively improved by an order of magnitude. Additionally, the composite passivation method not only improves the uniformity of the device, but also prevents the peeling of the S layer to improve the quality of passivation. This work offers a stable and high-quality passivation method, and it could be popularized passivation in the field of optics, electronics, optoelectronics, and switching devices.