sapphire substrate
3.The cleaning and nitridation effect of hydrogen and nitrogen ECR plasma for sapphire substrate are studied by analyzing RHEED image. The results indicate that we can markedly improve the cleaning effect of sapphire substrate by adding a small amount of nitrogen into ECR hydrogen plasma,thereby we can obtain smooth and clear substrate surface.
5.The SiO_2 abradant is used to polish the sapphire substrate and the temperature,pH value,diameter of the abradant particle and its concentration during the polishing are analyzed. The results show that using the abradant of 80 nm diameter and high concentration can obtain both high polishing rate and good surface topography.
6.Based on the relation images of RHEED for situ monitoring growth of GaN-based epitaxy film and surface feature epitaxy film. Details of transformation of the crystal lattice of growing surface of epitaxy film from RHEED images in different processes were given in this paper,such as hydrogen-nitrogen plasma cleaning,nitridation of sapphire substrate,growth of GaN buffer and AlN epilayer.
