A study was made of the evolution of defects, in n-type and p-type material which contained mainly residual group-I (Li, Cu) impurities in a donor or acceptor state, which occurred when it was stored in air at room temperature for six months. It was shown that the low-temperature photoluminescence intensity profiles which were measured over the thickness of a sample, after it had been briefly annealed in Cd vapor or in vacuum, varied appreciably with time and could provide information on the transformation of defects. In particular it was shown that, in the n-type regions of the samples, a decrease in the line intensity of excitons that were bound at neutral donors was determined by the loss, with time, of Li and Cu interstitial atoms to a defect sink. In the p-type regions, a decrease in the photoluminescence intensity was also associated with the formation of micro-inhomogeneities which gettered the impurities. The diffusion of LiCd and CuCd acceptors, and their spontaneous transition to Lii and Cui donor states, was also observed. It was concluded that the nature of the evolution of the defects, when samples were stored for a long time at room temperature, was determined by the initial state which was established the heat treatment.

V.N.Babentsov, A.I.Vlasenko, N.I.Tarbaev: Fizika i Tekhnika Poluprovodnikov, 1995, 29[9], 1563-9 (Semiconductors, 1995, 29[9], 813-6)