Effect of annealing in liquid cadmium upon photoluminescence in polycrystalline cadmium telluride grown under nonequilibrium conditions

The effect of annealing in liquid Cd at a temperature of 600$^\circ$C on the photoluminescence spectra of polycrystalline CdTe produced under conditions of rapid crystallization is demonstrated. It is shown that the annealing-induced redistribution of point defects completely suppresses the emission attributed to nonstandard acceptors with activation energies of $\sim$ 48, $\sim$ 98, and $\sim$ 120 meV and observed in the luminescence spectra of as-prepared crystals and radically modifies the emission structure in the range 1.2–1.35 eV, which corresponds to extended defects caused by twinning. In the photoluminescence spectra of the annealed poly-crystals, the emission related to exciton-impurity complexes involving hydrogen-like donors and CuCd acceptors is dominant. A correlation between the concentration of extended defects and the intensity of long-wavelength emission (in the range 0.8–1.2 eV) is established.