High-temperature processing of GaN: The influence of the annealing ambienton strain in GaN

Using micro-Raman scattering we have investigated the influence of the anne aling ambient on the high-temperature processing of GaN. Compressive strain is found in GaN layers after high-temperature processing in oxygen-contain ing atmospheres. This strain is significantly enhanced by the addition of w ater vapor to the annealing ambient, suggesting the enhanced inclusion of o xygen into GaN. Characteristic photoluminescence lines appear at 3.355 and 3.406 eV after annealing in oxygen in the presence of water vapor. No strai n is introduced by high-temperature processing in nitrogen ambient, even at temperatures close to the thermal decomposition temperature and in the pre sence of water vapor. (C) 1999 American Institute of Physics. [S0003-6951(9 9)03940-6].