Uncooled InAs-GaSb type-II infrared detectors grown on GaAssubstrates for the 8-12-μm atmospheric window

We report on the growth and characterization of type-II infrared detectors with an InAs-GaSb superlattice active layer for the 8-12-μm atmospheric window at 300 K. The material was grown by molecular beam epitaxy on semi-insulating GaAs substrates. Photoconductive detectors fabricated from the superlattices showed 80% cutoff at about 12 μm at room temperature. The responsivity of the device is about 2 mA/W with a 1-V bias (E=5 V/cm) and the maximum measured detectivity of the device is 1.3×10⁸ cm.Hz^1/2/W at 11 μm at room temperature. The detector shows very weak temperature sensitivity. Also, the extracted effective carrier lifetime, τ=26 ns, is an order of magnitude longer than the carrier lifetime in HgCdTe with similar bandgap and carrier concentration