Patent ID: 8476171

Claim:
A heat treatment method of a ZnTe single crystal substrate, comprising: a first step of increasing a temperature the ZnTe single crystal substrate to a first heat treatment temperature T 1 , and retaining the temperature of the substrate for a predetermined time; and a second step of gradually reducing the temperature of the substrate from the first heat treatment temperature T 1 to a second heat treatment temperature T 2 lower than the heat treatment temperature T 1 with a predetermined rate, wherein the first heat treatment temperature T 1 is set in a range of 750° C.≦T 1 ≦1250° C. and the second heat treatment temperature T 2 is set in a range of T 2 ≦T 1 −50, wherein in a Zn atmosphere of at least 1 kPa or more, a heat treatment including the first and second steps is performed not less than 40 cycles and for not less than 216 hours, and wherein the ZnTe single crystal substrate has a thickness of 1.5 mm or more.