Photovoltaic Detector Based on Type II Heterostructure with Deep AlSb/InAsSb/AlSb Quantum Well in the Active Region for the Midinfrared Spectral Range

Photodetectors for the spectral range 2-4 μm, based on an asymmetric typeII heterostructure pInAs/AlSb/InAsSb/AlSb/( p, n)GaSb with a single deep quantum well (QW) or three deep QWs at the het� erointerface, have been grown by metal-organic vapor phase epitaxy and analyzed. The transport, lumines� cent, photoelectric, current-voltage, and capacitance-voltage characteristics of these structures have been examined. A highintensity positive and negative luminescence was observed in the spectral range 3-4 μm at high temperatures (300-400 K). The photosensitivity spectra were in the range 1.2-3.6 μm (T = 77 K). Large values of the quantum yield (η = 0.6-0.7), responsivity (Sλ = 0.9-1.4 A W -1 ), and detectivity ( = 3.5 × 10 11 to 10 10 cm Hz 1/2 W -1 ) were obtained at T = 77-200 K. The small capacitance of the structures (C = 7.5 pF at V = -1 V and T = 300 K) enabled an estimate of the response time of the photodetector at τ = 75 ps, which corresponds to a bandwidth of about 6 GHz. Photodetectors of this kind are promising for heterodyne detec� tion of the emission of quantumcascade lasers and IR spectroscopy.