Low dark current InAs/GaSb type-II superlattice infrared photodetectors with resonant tunnelling filters

Abstract

InAs/GaSb type-II strained-layer superlattice (SLS) photovoltaic infrared (IR) detectors are currently of great interest for mid- and long-wave IR detection. A novel technique of reducing detector dark current by inserting resonant tunnelling barriers into a conventional InAs/GaSb SLS is investigated. The GaSb/InAs/GaSb resonant tunnelling double barrier heterostructure was designed to be periodically inserted into a conventional InAs/GaSb SLS detector to block thermally excited electrons, while permitting photo-excited electrons to tunnel through. The measured dark current density of the tunnelling InAs/GaSb SLS detector in the entire negative bias range is lower than that of the conventional SLS detector by a factor of about 3.8 at 77 K. At 84 K, the Johnson-noise-limited detectivity of the tunnelling detector, measured at 4 µm, is 18% higher than that of the conventional detector. Both the conventional and the tunnelling SLS detectors demonstrated high-temperature operation, up to 300 K.