Heat treatment of cadmium mercury telluride

A method for the heat treatment of homogeneous single crystal cadmium mercury telluride represented by the formula (Cd.sub.x Hg.sub.1-x).sub.y Te.sub.1-y wherein x has values between zero and one and y has values in the range of about 0.49 to 0.51 in an ampoule, comprising the steps of placing in said ampoule slices of said cadmium mercury telluride and a predetermined amount of mercury, evacuating and sealing the ampoule, heating the ampoule to a constant uniform temperature in the range of from about 300 K. to a temperature near but below the solidus temperature of said slices of cadmium mercury telluride, said predetermined amount of mercury being such that only vapor of said predetermined amount of mercury is present in the ampoule at said constant uniform temperature and the vapor pressure of mercury is less than the saturation vapor pressure of mercury at said constant uniform temperature, maintaining said constant uniform temperature for a period in the range of about 1 to 5000 hours, and recovering treated slices.