Spatial phase separation of GaN selectively grown on a nanoscale faceted Si surface

Abstract

This letter reports the growth of spatially separated hexagonal and cubic phases of GaN on a patterned Si(001) substrate by metalorganic vapor-phase epitaxy. The substrate surface was patterned with grooves having a 355 nm period. Each groove consisted of two opposed Si{111} facets that were separated by Si(001) surfaces. Epitaxial growth of GaN on this substrate began selectively on the Si{111} facets and yielded the GaN hexagonal phase. With further growth, the two hexagonal phase regions separately grown on the opposed Si{111} facets coalesced, with strongly misaligned c axes (∼110°). The GaN grown after coalescence was subsequently confirmed, by transmission electron microscopy and photoluminescence, to be of cubic phase.