Annealing behavior of bound exciton lines in high quality CdTe

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Abstract
Annealing behavior of shallow donor‐bound and acceptor‐bound exciton lines in CdTe crystals grown by the Bridgman method was investigated by high‐resoluton photoluminescence measurements at 4.2 K. The intensity of the neutral acceptor‐bound exciton line (A0X) at 1.5896 eV, which was commonly observed in p‐type CdTe, drastically decreased by annealing under Cd saturated atmosphere. By further subsequent annealing under Te saturated atmosphere, the A0X line recovered again. On the other hand, the intensity of the neutral donor‐bound exciton line increased by annealing under Cd saturated atmosphere and decreased by the further annealing under Te saturated atmosphere. It was found that this change in the photoluminescence lines by the annealing process was reversible. These results strongly suggest that the A0X line at 1.5896 eV can be ascribed to the recombination of excitons trapped at Cd‐vacancy/donor‐impurity complexes.