Using flow modulation organometallic vapor phase epitaxy, a process has been developed which produces epitaxial lateral overgrowth of GaN-base materials directly on SiC and sapphire substrates patterned with silicon nitride. The key feature of this single step process is the use of a high temperature AlGaN nucleation layer which wets the exposed substrate surface, without significant nucleation on the mask. This eliminates the need for regrowth while producing smooth growth surfaces in the window opening as well as over the mask. Subsequent GaN deposition results in relatively defect free materials grown laterally over the mask. Using arrays of stripe windows aligned parallel to the 〈100〉
crystal direction, the epitaxial films completely planarize after roughly 5 microns of growth. Defect densities estimated from atomic force micrographs indicate a reduction from mid 108
to 105 cm−2
in regions over the window and over the mask, respectively. This process represents a significant simplification over currently used regrowth methods for obtaining low defect density laterally overgrown GaN materials. © 1999 American Institute of Physics.