The ultimate IRFPA will operate at room temperature and exhibit background limited performance (BLIP), regardless of the operating cutoff wavelength. Currently the primary vehicle for room-temperature IR detection is the thermal detector, but it is essentially limited to the detection of LWIR radiation, at relatively slow frame rates, or integration times. These limitations were discussed briefly in Sec. 2.2 for the optimized perfect thermal detector. The successful room-temperature detection of the complete IR spectrum, with BLIP performance, will require the utilization of other detector concepts. The HOT detector of Elliott and Ashley  is just such a concept, the potential of which is limited entirely by the quality of the direct bandgap semiconductor utilized to detect the IR radiation and the contacts and passivation applied to that material. The HgCdTe HOT detector concept is discussed here, together with a consideration of relevant material properties within the active volume of the device for successful room-temperature operation, taking into account the all-important issue of Shockley-Read (S-R) centers in HgCdTe. The HOT concept is not limited to the HgCdTe materials system alone, but it can be implemented in any direct bandgap semiconductor material or its bandgap engineered equivalent.
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