Heterojunction-based GaSb/InAs strained-layer superlattice long wavelength infrared detectors

Design parameters for the heterojunction-based strained layer superlattice (SLS) long-wave infrared (LWIR) detector are investigated so that it operates at a lower bias voltage with lower dark current and higher photo response. At typical operating temperatures (T ∼ 77 K), the dark current of GaSb/InAs SLS LWIR detectors is dominated by the Shockley–Read–Hall (SRH) generation–recombination (g–r) process in the space-charge (depletion) region. In order to suppress this dark current, a wide bandgap region next to the absorber layer has been included in recent SLS designs. A series of heterojunction-based LWIR SLS detectors with various doping and barrier profiles have been designed and characterized. The significance of the doping profile and thickness of the wide-bandgap layer in optimization of the heterojunction-based SLS detector performance are exhibited from the modeling and experimental results of these devices.