Improvement of Surface Morphology of RF MBE Grown (0001) GaN via In-Protected Growth Interruption Modulation

GaN layers have been deposited on (0001) sapphire substrates using radio frequency molecular beam epitaxy by In-protected growth interruption modulation.The growth process is monitored by in-situ reflection high-energy electron diffraction.The morphological and structural properties of GaN films are investigated by scanning electron microscopy,atomic force microscopy,and X-ray diffraction (XRD).The results indicate that the density of gallium droplets on the GaN surface is greatly reduced,and the morphology of the GaN films is improved.The RMS is reduced to 0.6nm,while it is 3nm without using this technique.Furthermore,the XRD rocking curves show that the structural quality of the films is superior to that of GaN films formed without using this technique.