Extension of longwavelength IR photovoltaic detector operation to near room-temperatures

Abstract Practical realization of near room temperature (230–300 K) longwavelength (5–12 μm) photovoltaic detectors is reported. The devices are epitaxial n+ip p photodiodes operated at ambient temperature or with a simple, two-stage thermoelectric cooling. The performance of the photodiodes has been improved by the use optimized composition and doping profile structures. The tunnel currents were minimized by interfacing the n+ and p-type layers with a thin (0.5 μm) lightly doped i-region. The quantum efficiency has been increased by the use of backside reflector. Further improvement of performance was achieved by the use of monolithic optical immersion. Large area devices with useful performance were obtained by the use of small close-spaced elements connected in series. The near room temperature photovoltaic detectors are of particular significance for very low and very high frequency applications.