Anodic fluoride passivation ofInAs/GaSb superlattice for mid-/short-wavelength dual-color infrared detector

Abstract

Herein, we report a novel approach to passivation of InAs/GaSb superlattice for mid-short wavelength dual-color infrared detector. One of the major challenges faced by InAs/GaSb superlattice devices arises owing to the large number of surface states that are generated. Surface passivation and subsequent capping of the surfaces are absolutely essential for any practical applicability of this material system. As evidenced by the comparison of unpassivated and passivated InAs/ GaSb superlattice mid-short wavelength dual-color infrared photodiodes. The surface passivation methods include zinc sulfide (ZnS) coating after anodic oxide, and ZnS coating after fluoride passivation. InAs/GaSb superlattice infrared materials were grown by molecular beam epitaxy on GaSb (100) substrates. A GaSb buffer layer, which can decrease the occurrence of defects with similar pyramidal structure, was grown for optimized superlattice growth condition. The reliability of passivation by anodic fluoride was confirmed by AES. The leakage current as a function of bias voltage (J–V) for superlattice diodes obtained using different passivation methods has been examined at 77 K. The best performance was demonstrated by the ZnS after anodic fluoride passivation.