Growth of single-domain GaN layers on Si(0 0 1) by metalorganic vapor-phase epitaxy

Highly oriented wurtzite-type GaN layers were grown on Si(0 0 1) substrates by metalorganic vapor-phase epitaxy. The use of a high-temperature AlN seed layer at more than 1100 °C allows growing solely c-axis-oriented crystallites. However, due to the symmetry of the Si(0 0 1) surface two in-plane alignments of the GaN occur, twisted by 30°. Therefore, to obtain a coalesced GaN surface, the selection of only one certain orientation is necessary. The approach of 4° off-oriented substrates enabled to grow a flat, highly mono-oriented GaN layer on Si(0 0 1), with both kinds of in-plane alignments realizable. The crystalline quality of the GaN was investigated by X-ray analysis and scanning electron microscopy.