Microstructural analysis of III-V nitrides grown on 6H-SiC by metal-organic vapour phase epitaxy (MOVPE)

We have studied the growth mechanisms of GaN and AlGaN layers with low alum inium incorporation (<7%) deposited by metal-organic vapour phase epitaxy ( MOVPE) on 6H-SiC. The direct growth of GaN leads to isolated islands. For A lGaN alloys, the growth can be either three-dimensional or two-dimensional depending on the proportion of aluminium in the vapour phase. Aluminium-ric h seeds, whose density depends on the aluminium incorporation in the alloy and on the 6H-SiC surface preparation, act as nucleation centres and enable one to obtain flat layers after lateral coalescence. (C) 2000 Elsevier Sci ence S.A. All rights reserved.