Luminescence and influence of defect concentration on excitons in Hg-197/Au-197-doped CdTe

CdTe, implanted with Hg-197 ions, which decay to Au-197 With a half-life of 64.1 h, was investigated by photoluminescence (PL) spectroscopy. The resul ts unambiguously verify the assignments of bath, the donor-acceptor pair tr ansition at 1.335 eV, which corresponds to an acceptor level with E-A = 263 meV, and the recombination of excitons bound to neutral accepters at 1.576 06 eV to single Au atoms on Cd sites. In addition, the dependence of the in tensities of excitonic lines on the defect concentration was investigated q uantitatively. The observed intensities are well explained, assuming that a defect can only bind an exciton if there is no additional defect within th e volume of the bound exciton. The ratio between the exciton radii of the C u- and Au-bound excitons R-exe(Cu)/R-exe(Au) = 1.2 +/- 0.2 obtained from th is model is in good agreement with the ratio derived from the diamagnetic s hift parameters of the two corresponding PL lines. (C) 1999 Elsevier Scienc e B.V. All rights reserved.