Optimized structural properties of wurtzite GaN on SiC(0001) grown by molecular beam epitaxy

We have investigated the optimal conditions for molecular beam epitaxial gr owth of high quality GaN on 6H-SiC(0001) substrates. The quality of these f ilms is reflected both by the narrow x-ray peak widths as well as the excel lent surface morphology. In this work, it is shown that increasing growth t emperature leads to an improvement in bulk quality and lower x-ray peak wid ths for both symmetric and asymmetric reflections. We also note a marked im provement in surface morphology, from a columnar appearance to a two-dimens ional surface, under extremely Ca-rich growth conditions. (C) 2000 American Vacuum Society. [S0734-2101(00)04904-6].