High operating temperature InAs/GaSb type-II superlattice detectors on GaAs substrate for the long wavelength infrared

We report on the development of InAs/GaSb type-II superlattice infrared photodetectors for operation under temperatures reachable with thermoelectric cooling. We investigate optically immersed, laterally operated photoconductors with a cutoff wavelength around 10 μm at an operating temperature of 200 K. The identification of a suitable superlattice composition, the growth of a linearly graded metamorphic buffer layer and the transfer of the device concept from GaSb to GaAs are motivated and described. We show that immersion lens technology even for non-doping optimized devices enables a peak spectral detectivity above 6×109 cm Hz0.5W−1 at 195 K, approaching the performance of commercially available HgCdTe-based photoconductors.