Identification of Ag-acceptor related photoluminescence in $^{111}\!$Ag doped CdTe

Bridgman-grown, nominally undoped CdTe crystals were doped with Ag by implanting radioactive $^{111}\!$Ag. Photoluminescence spectra of the crystals show a donor-acceptor pair (DAP) line at 1.491 eV. The decrease of the intensity of this line with a half life of T$_{1/2}$=(7.2$\pm$0.4) d is in good agreement with the half life of the $\beta\!^{-}$-decay of $^{111}\!$Ag to $^{111}\!$Cd of 7.45 d. This decrease is not caused by the aging behavior of Ag which was reported in the literature. The data show that the involved acceptor defect contains exactly one Ag atom and confirm the earlier assignment of the acceptor to the AgCd defect. Based on the DAP line at 1.491 eV, the spectra did not reveal a contamination of the CdTe crystals by stable Ag.