Effects of two-step annealing on properties of Cd1-xZnx single crystals
(1.College of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
2.Institute of M aterials Science and Engineering, Shanghai U niversity, Shanghai 200072, China)
2.Institute of M aterials Science and Engineering, Shanghai U niversity, Shanghai 200072, China)
Abstract: Cd1-xZnxTe(CZT) single crystals were annealed by a two-step method including a vapor-environment step and a liquid-environment step in sequence. The effects of annealing on the properties of CZT were analyzed in detail. IR transmission measurement results show that IR transmission of CZT is improved dramatically after annealing. X-ray rocking curves indicate that the annealing treatment ameliorates crystal quality obviously, which is ascribed to the release of residual stress and the reduction of point defects. Photoluminescence(PL) spectra reveal that the full width at half maximum(FWHM) of the donor-bound exciton (D0, X) peak is reduced obviously, and the free exciton emission is weakened after annealing. Meanwhile, the intensity of the donor-acceptor pair(DAP) peak decreases to a great degree, which implies that the impurities are removed from CZT wafers. In addition, the deep defect-related emission band Dcomplex disappears after annealing, which mean that Cd vacancies are well-compensated. The results confirm that the two-step annealing is an effective approach to improve the qualities of CZT single crystals.
Key words: Cd1-xZnxTe single crystal; impurities; defects; semiconducting II-VI materials