ACTIVATION OF ACCEPTORS IN MG-DOPED GAN GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

The activation kinetics of accepters was investigated for heteroepitax ial layers of GaN, doped with Mg. After growth, the samples were expos ed to isochronal rapid thermal anneals in the temperature range from 5 00 to 775 degrees C. The samples were studied by variable temperature Hall effect measurements and photoluminescence (PL) spectroscopy in th e as-grown condition and after each temperature step. The thermal trea tment reduced the resistivity by six orders of magnitude and the p-typ e conductivity was found to be dominated by an acceptor with an activa tion energy of similar to 170 meV. This acceptor is attributed to Mg a toms substituting for Ga in the GaN lattice and the activation process is consistent with dissociation of electrically inactive Mg-H complex es. It is shown that the appearance of a blue emission band in the PL spectrum of Mg-doped GaN does not directly correlate with the increase in p-type conductivity. (C) 1996 American Institute of Physics.