Local vibrational modes in Mg-doped GaN observed by Raman scattering

Local vibrational modes related to Mg and H atoms are observed by Raman scattering in Mg-doped GaN films grown by chemical vapor deposition using hydrogen as the carrier gas. First, activation process of Mg by annealing in N-2 ambiance was studied at annealing temperatures between 500 degreesC and 1000 degreesC. Raman spectra showed that in as-grown films Mg atoms in Ga site is passivated by H atoms bound to Mg-N bonds. The H atoms are released by annealing at above similar to 600 degreesC, and p-type conductivity is obtained. Second, p-type conductive films were annealed in NH3 ambiance. The spectra showed that high density of H atoms are incorporated in the film at above similar to 700 degreesC, and p-type conductivity is lost. Both results suggest that H atoms bound to Mg-N play key roles in the activation or deactivation process.