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.