Donor-hydrogen bound exciton in epitaxial GaN

An emission, named (D-2(0),X), located at similar to 3.48 eV at low temperature, in the near-band-edge spectrum of GaN, was investigated by photoluminescence (PL). This (D-2(0),X) emission is close in energy to the well-studied neutral-donor-bound-exciton (D-0,X) line in GaN. They are distinguished by a variety of PL measurements in this study. Excitation power and temperature-dependent studies indicate that this emission is related to a bound exciton complex. Annealing at a relatively low temperature similar to 440 degrees C results in a dramatic reduction of the PL intensity of this emission. A model is proposed that the exciton-binding center responsible for the (D-2(0),X) emission consists of a (shallow) donor-hydrogen complex that is formed in the GaN epilayer during the growth. The annealing at 440 degrees C results in the dissociation of this complex and thus reduces the PL intensity of the (D-2(0),X) emission. [S0163-1829(99)00444-0].