Focal-plane arrays of HgCdTe photoconductors have been designed and fabricated to satisfy special requirements for high-performance long-wavelength infrared (LWIR) photodetectors. The special requirements are the following:

  • The photoconductive LWIR photodetectors must offer high response and low noise in detection of radiation at wavelengths from 9.1 to 16.6 µm.
  • The electrical characteristics of the photoconductive LWIR photodetectors must include high resistance and low power dissipation.
  • Each array of the photoconductive LWIR photodetectors must be buttable against another, separately manufactured array of photovoltaic devices on the same focal plane for detecting radiation at wavelengths from 7.1 to 9.1 µm.

The design features a split geometry with all electrical leads on one side of each array; this aspect of the design ensures the required buttability. Furthermore, split-geometry photoconductive detectors inherently have larger current path lengths and resistances than do those of nonsplit geometry; as a result, detector responses are greater and less power is dissipated.

The arrays operate with detectivity of about 3 to 4 ×1010cm Hz 1/2 /W cutoff wavelength as long as 18 µm. They satisfy all of the special requirements described above. The original application to which the special requirements pertain is to spacecraft instrumentation aboard the CIRS/Cassini spacecraft. There is need for arrays of similar design in other spacecraft; for example, detectors and arrays with similar design are being developed for the Geostationary Operational Environmental Satellite (see the following article). There is also a potential market in terrestrial, scientific, commercial, and military remote-sensing applications.

This work was done by Bob Martineau, Andre Burgess, Sridhar Manthripragada, Frank Peters, Brent Mott, and Peter Shu of Goddard Space Flight Center; Kelley Hu and Jack Shi of HSTX; and Sachidananda Babu of Ball Aerospace. For further information, access the Technical Support Package (TSP) free on-line at  under the Electronic Components and Systems category. GSC-13812