Photoluminescence analysis of Cd_1-xZn_xTe single crystals annealed by a two-step method

Cd_1-xZn_xTe (CZT) single crystals were annealed by a two-step method, including a vapor-environment step and a liquid-environment step in sequence. Photoluminescence spectra were used to investigate the effects of annealing on the properties of CZT. After annealing the full width at half maximum of the donor-bound exciton (D⁰,X) peak was reduced, and the free-exciton emission was weakened. Meanwhile, the intensity of the donor-acceptor pair peak was greatly decreased. In addition, the deep defect-related emission band D_complex disappeared after the annealing, which was distinct for as-grown CZT wafers. The investigation confirms that the two-step annealing can compensate for cadmium vacancies and possibly reduce the impurities from CZT wafers.