ELECTRONIC-PROPERTIES OF A CENTERS IN CDTE - A COMPARISON WITH EXPERIMENT

The temperature variation of the A-center (a cadmium-vacancy halogen-d onor pair) luminescence has been calculated using a temperature-depend ent electron-ion interaction. The photoluminescence lines of the A cen ter show a pronounced shift with temperature between 4 and 50 K. The z ero-phonon line is explained in terms of a donor-acceptor pair transit ion and the temperature dependence is not due to the thermal expansion of the CdTe crystal. It results from excitations of electrons from sh allow levels of isolated halogen donors and from transitions from the conduction-band edge to the deep acceptor level of the A center.