Relaxation of anisotropic domain tilting along vertical growth direction in selectively lateral overgrown GaN by hydride vapor phase epitaxy

Anisotropic domain tilting of GaN films prepared by hydride vapor phase epi taxy (HVPE) on GaN/sapphire (0 0 0 1) substrate employing lateral epitaxial overgrowth (LEO) method has been investigated using high-resolution X-ray diffraction. Anisotropic domain tilting resulted in anisotropic broadening of GaN (0 0 0 2) Bragg peak and anisotropicity was fitted using a model bas ed on anisotropic mosaic spreading. Anisotropicity of domain tilting, which was thought to be induced by stress gradient in the transition area betwee n prepatterned SiO2 stripes and window region, relaxed with an increasing f ilm thickness, but was still observed to exist up to a film thickness of 40 mu m. (C) 2000 Elsevier Science B.V. All rights reserved.