Surface analysis of GaN decomposition

Abstract

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 N2 loss at elevated temperatures. Additionally, the emergence of a direct scattering peak approximately 0.25μm beneath the surface at 1100 °C 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 N2 up to 900 °C. At higher temperatures, significant decomposition occurs and gives rise to degradation of the structural and morphological properties of the film.