Infrared focal planes in intrinsic semiconductors

In this paper, we review the state-of-the-art of intrinsic semiconductor detector arrays and project future areas of development. Infrared focal planes in intrinsic semiconductors offer advantages over extrinsic semiconductor structures in both operating temperature and quantum efficiency. Although the device function of spectral filtering and detection of the incident photon flux is now well understood in intrinsic semiconductors, the function of signal processing has only recently been investigated. As a result, research is directed toward implementation of both hybrid devices, in which the signal processing is accomplished in a silicon multiplexer which is physically and electrically interfaced with an intrinsic semiconductor detector array, and monolithic charge transfer devices in which detection and signal processing are accomplished in the same semiconductor. In the monolithic approach, charge transfer devices have been demonstrated in InSb, and it is likely that similar devices will be realized in InSb related alloys and HgCdTe in the near future. Demonstration of a non-MIS charge transfer design would open up the monolithic approach to the IV-VI alloys. Hybrid focal planes incorporating ≳ 1000 element photodiode arrays have been realized in the III-V and the IV-VI alloys; the detector-multiplexer interface circuit will remain one of the key technical issues in the achievement of a high-performance hybrid focal plane.