Mechanism of Yellow Luminescence in GaN

Abstract

The mechanism of the yellow luminescence in GaN has been studied. The yellow band is observed in microcrystals synthesized from Ga and NH3 by direct reaction, but is not observed in needle-like crystals grown by sublimation-recrystallization. Doping with carbon emphasizes the yellow band. The characteristic excitation band is observed in C-doped GaN. The yellow band is due to a radiative transition from a shallow donor with a depth of 25 meV to a deep acceptor with a depth of 860 meV. The relation between the characteristic excitation band and the emission band is interpreted by the simple configuration coordinate model. The deep acceptor is thought to be a complex consisting of a gallium vacancy and a carbon atom substituted for a nearest neighbour of the gallium sites.