Radioactive Isotopes in Photoluminescence Experiments: Identification of Defect Levels

The characteristic lifetimes of radioactive isotopes can be used to label and identify defect levels in semiconductors which can be detected by photoluminescence (PL). This is demonstrated in GaAs doped with radioactive ${}^{111}$In. During its decay to ${}^{111}$Cd all those PL peaks increase for which Cd acceptors are involved. By deriving a quantitative relation between PL intensity and Cd concentration we show that this intensity increase is determined only by the nuclear lifetime of ${}^{111}$In. Thus we gain a complete and independent identification of the Cd related PL peaks in GaAs.