The electronic structure of bound electrons which involved native defects and point defects was investigated by making optical spectroscopic studies of highly crystalline samples. It was demonstrated that the interactions of single particles were responsible for the splitting of the (Do,X) and (Ao,X) states. From these splittings, the hole-hole interaction parameter and the cubic crystal-field parameter for the Li bound exciton complex were determined unambiguously for the first time. The I1d emission line exhibited a fine structure which was similar to the I1Li exciton line. The I1d was therefore attributed to acceptor-bound exciton recombination with an associate which was formed from a Zn vacancy and an impurity donor, which combined to act as an acceptor.

U.W.Pohl, G.H.Kudlek, A.Klimakow, A.Hoffmann: Journal of Crystal Growth, 1994, 138[1-4], 385-90