ORIGIN OF THE BLUE LUMINESCENCE OF BETA-GA2O3

Electrons in donor states of gallium oxide exhibit a paradoxical behav ior. On the one hand they exhibit free electron properties such as imp urity band conduction and motionally narrowed ESR signals at liquid he lium temperature, while on the other hand they are responsible far a b lue luminescence characterized by a strong electron-phonon coupling. T he time decay and the temperature dependence of the blue luminescence upon specific excitation of the acceptor defects were investigated and a model for the donor V-O(X) and acceptor (V-O, V-Ga)' microstructure is proposed. Donors would be assembled in shallow clusters responsibl e for delocalized electron behavior with minority accepters between. T he blue luminescence would result from the fast recombination of an ex citon trapped at an acceptor site after a rate determining tunnel capt ure of an electron from a donor cluster. (C) 1998 Elsevier Science Ltd . All rights reserved.