Method for preparing Te-Zn-Cd monocrystal in large volume

This invention discloses a method for preparing large-volume cadmium zinc telluride (CZT) single crystal. The method comprises: (1) selecting high-melting-point CZT single crystal as the seed crystal; (2) coating a carbon film on the inner side of a quartz ampoule, placing CZT seed crystal in the seed crystal bag at the bottom of the ampoule so that the seeding growth surface of CZT seed crystal is upward, then adding low-melting-point CZT polycrystal, vacuumizing the quartz ampoule, and sealing by welding; (3) placing the quartz ampoule into an ACRT-B type crystal growth apparatus, heating the temperatures of the high-temperature zone and the low-temperature zone to 1135-1145 deg.C and 1030-1040 deg.C within 18-20 h, overheating for 12-16h, and descending the supporting bar at a speed of 0.8 mm/h for 200-240 h; (4) cooling the high-temperature zone and the low-temperature zone to 870-890 deg. within 5-6 h, annealing the crystal ingot in situ for 144-168 h, then slowly cooling to 550-560 deg.C at a rate of 5 deg.C/h, shutting off the power source, and cooling to room temperature. The method can obtain large-volume CZT single crystal, and increase the single crystal ratio in the crystal ingot.