Very-Long-Wavelength Infrared Range Type-II Superlattice InAs/InAsSb GaAs/Immersed Photodetectors for High-Operating-Temperature Conditions

Recently, there has been significant interest in type-II superlattice (T2SL) infrared detectors based on both InAs/GaSb and InAs/InAsSb material systems, and fully operating devices have been presented in the mid- (MWIR) and long-wavelength (LWIR) infrared ranges. In addition, theoretical simulations and experimental reports show high-performance T2SL devices in the very-long-wavelength infrared range (VLWIR) (cutoff wavelength, λc ≥ 12 μm). Devices in this wavelength range are essential for space-based applications. In VLWIR, the existing detectors with satisfactory performance are extrinsic silicon detectors operating under heavy, bulky and short-lifetime multistage cryocoolers. These disadvantages are mainly critical for space applications, and thus, developing a device exhibiting a higher operating temperature (HOT) is of high priority. We report on a photoconductive T2SL InAs/InAsSb detector with λc > 18 μm (limited by a GaAs substrate) and high-operating-temperature (HOT) conditions (T = 210–240 K) grown on thick semi-insulating GaA substrates by molecular beam epitaxy (MBE).