Compound-source molecular beam epitaxy of GaN using GaN powder and ammonia as sources

Compound-source molecular beam epitaxy (CS-MBE) of GaN layers using GaN powder and ammonia as sources is discussed. In particular, the reduction of excess Ga in GaN layers by introducing ammonia supply is discussed on the basis of their refraction high-energy electron diffraction (RHEED) patterns, X-ray photoelectron spectroscopy (XPS) spectra and atomic force microscopy (AFM) images. It was clarified that the ammonia supply is effective for the high growth rate of GaN layers and for the reduction of their oxygen concentration. During the growth, the surface migration of Ga atoms is limited by the ammonia supply.