OBSERVATION OF PREFERENTIAL DONOR-ACCEPTOR PAIRING IN ZNSE-NA

Donor-acceptor preferential pairing can occur in compensated semicondu ctors due to the Coulomb attraction between ionized donors and accepto rs. However, extensive preferential pairing requires high ion mobiliti es at relatively low temperatures, and has been very difficult to esta blish conclusively. We here report identification of such preferential pairing, from donor-acceptor pair luminescence in two samples of Na-d oped ZnSe. We observed essentially identical close pair lines (both in location and in relative intensity) in both samples, but the associat ed distant pair peak was observed at a higher energy in one sample tha n in the other. We explain this by assuming that there is strong prefe rential pairing in the first sample and weaker pairing in the second s ample. Our observation of preferential pairing also shows that one can have high ion mobilities in ZnSe.