The decomposition of GaN at temperatures ranging from 500degreesC to 1100degreesC has been studied by Rutherford backscattering (RBS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The development of a surface defect peak is a consequence of preferential N-2 loss at elevated temperatures. Additionally, broadening of the defect peak at 1100 degreesC, corresponding to a damage depth of approximately 0.25 mum beneath the surface, can be attributed to the diffusion of defects from the interface. At such temperatures, severe roughening of the surface is observed through AFM scans, which also correlated well with the damage depths estimated from RBS spectra. Nevertheless, Ga droplet formation is not detected from our samples as verified by XPS. Our results show that GaN remains thermally stable in N-2 up to 900 degreesC. At higher temperatures, significant decomposition occurs and gives rise to degradation to the structural and morphological properties of the film. (C) 2003 American Vacuum Society.