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Low dark current in mid-infrared type-II superlattice heterojunction photodiodes

: Schmidt, Johannes; Rutz, Frank; Wörl, Andreas; Daumer, Volker; Rehm, Robert


Infrared physics and technology 85 (2017), S.378-381
ISSN: 1350-4495
Fraunhofer IAF ()
InAs/GaSb type-II superlattice; T2SL; MWIR; Infrared detector; heterojunction; dark current density; Key Publication

A mid-infrared (MWIR, 3–5 μm) InAs/GaSb type-II superlattice (T2SL) photodiode device with very low dark current is presented. The novel heterojunction device is compared to a conventional pn-homojunction device. Photodetectors with reduced dark current allow an increased operating temperature and thus to lower the cooling requirements for high performance infrared imaging applications. We report on a dark current reduction by a factor of more than 100 at a typical operation voltage of −100 mV at 77 K, which was realized merely by device design. This measured dark current is the lowest reported to our knowledge for T2SL-detectors operating in the 3–5 μm range. At the same time, the photo current signal is unaffected by the heterostructure design over the entire bias voltage range.