Observations were made, of the narrower structures in the yellow luminescence of bulk and film samples of n-type GaN material, by using the selective excitation technique. The fine structures exhibited a thermal quenching which was associated with an activated behavior. The fine structures were attributed to phonons and electronic excitations of a shallow donor-deep acceptor complex, and its activation energy for delocalization was determined. The results suggested that, in addition to distant donor-acceptor pairs, the yellow luminescence could also involve emission complexes of shallow donors and deep acceptors.

Selective Excitation and Thermal Quenching of the Yellow Luminescence of GaN. J.S.Colton, P.Y.Yu, K.L.Teo, E.R.Weber, P.Perlin, A.Grzegory, K.Uchida: Applied Physics Letters, 1999, 75[21], 3273-5