Low-energy ion assisted deposition of epitaxial gallium nitride films

Epitaxial gallium nitride thin films were grown on c-plane and r-plane sapphire: by low-energy ion assisted deposition in high vacuum using a constricted glow discharge plasma sourer for the supply of nitrogen. Instead of preparing a conventional low-temperature buffer layer, a single-temperature process with initial growth rate ramp was performed. The crystallographic structure and texture, defect distribution, morphology and topography of the grown films were investigated with X-ray diffraction techniques, channeling-RBS, TEM and AFM, respectively. The ion assisted growth procedure results in well-oriented, epitaxial, single crystalline, wurtzitic GaN films with low defect densities. The film surfaces are generally smooth, but show either holes or clusters indicating unbalanced gallium and nitrogen fluxes during growth. (C) 1999 Elsevier Science B.V. All rights reserved.