Surface analysis of GaN decomposition

The decomposition of GaN at a range of temperatures 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, the emergence of a direct scattering peak approximately 0.25 mum beneath the surface at 1100 degreesC can be attributed to the buildup of extended defects. At such temperatures severe roughening of the surface is observed through AFM scans. 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 of the structural and morphological properties of the film.