ANALYSIS OF MBE GROWTH MODE FOR GAN EPILAYERS BY RHEED

The growth mode of hexagonal GaN epilayers on sapphire(0 0 0 1) surfac es during N-2 plasma-assisted molecular beam epitaxy was investigated using in situ reflection high-energy electron diffraction technique. I t was found that the Ga-rich condition results in a flat surface showi ng streak patterns rather than the N-rich condition, and the intensiti es of the diffraction spots show behaviors that are different for Ga-r ich and N-rich conditions. For the specular spot, oscillation-like int ensity variations were observed according to the supply of Ga flux, wh ich depends on Ga flux intensity and substrate temperature. At the low er temperature region, the growth of cubic GaN was observed with its [ 1 1 1] crystal axis along the normal direction of the sapphire(0 0 0 1 ) surface. (C) 1998 Elsevier Science B.V. All rights reserved.