Photoluminescence in high-resistivity CdTe : In

Abstract

Photoluminescence measurements have been performed at 4.2 K between 1.2 and 1.6 eV on compensated high-resistivity CdTe containing from 1015 to 1018 cm−3 indium. A series of phonon-coupled emission bands with a no-phonon peak at 1.454 eV is dominant in most samples and grows in intensity with increasing In concentration. On the basis of the compensation model, the 1.454-eV emission is attributed to radiative recombination at an [cadmium vacancy-In] acceptor complex. Comparison of the experimental results with this model suggests that the chemical equilibria governing formation of the acceptor complex are frozen in at approximately 500 K as the sample is cooled from the growth temperature. The existence of significant changes at 500 K in the mobility of defects related to the acceptor complex is confirmed by the observation of a prominent growth in the 1.454-eV emission at an annealing temperature of 500 K in A+-implanted n-type CdTe. Exciton emission in the CdTe : In samples is dominated by a narrow bound exciton band at 1.584 eV which is assigned to recombination at a center associated with In. Edge emission is relatively weak in all samples with the peak positions varying from 1.538 to 1.546 eV.