A 40-fold reduction in density of vertical threading dislocations at the surface of GaN was obtained with cantilever epitaxy by using narrow (less than 1μm) mesas etched into a sapphire substrate and conditions producing angled {11•2} facets to initiate growth by metalorganic chemical vapor deposition. These 2 techniques redirect vertical threading dislocations over the mesas to the horizontal and away from device areas above. Further reductions appeared possible if the facets uniformly cover all mesas prior to cantilever growth.

Minimizing Threading Dislocations by Redirection during Cantilever Epitaxial Growth of GaN. D.M.Follstaedt, P.P.Provencio, N.A.Missert, C.C.Mitchell, D.D.Koleske, A.A.Allerman, C.I.H.Ashby: Applied Physics Letters, 2002, 81[15], 2758-60