Mercury cadmium telluride as an infrared detector material

The properties of the alloy semiconductor Hg 1-x Cd x Te and its application as an infrared detector material are reviewed. The selection of this alloy system as an infrared detector material is discussed. Bulk and epitaxial crystal growth techniques are described and representative electrical data presented which show the free carrier concentration to be in the 10 14 -10 15 cm -8 range. The flexibility of this ternary system is then discussed relative to the compositional dependence of the energy gap. Photoconductive response data are presented for detectors having response peaks of 4-20 microns over the temperature range 15°-300°K. The expression E g = 1.6(x - 0.134) + 0.1335(0.435 - x)(T/100 -1) 40° < T < 240°K 0.15 < x < 0.35 is shown to represent the compositional and temperature dependence of the energy gap within the specified limits.