Electron microscopic analyses were made of the microstructures of epitaxial laterally overgrown GaN. It was found that dislocations lying on (00•1), or horizontal dislocations, were generated in epitaxial lateral overgrown GaN layers overlaying a mask of a-SiO2. The horizontal dislocations had the shape of a loop or semi-loop, and the morphology suggested that the horizontal dislocations were generated via a multiplication mechanism, with the assistance of internal stress. On GaInN/GaN, a pit was formed at the end of a threading dislocation with any Burgers vector: a, c or a+c. The density and distribution of threading dislocations in epitaxial lateral overgrown GaN could be estimated by observing these growth pits after the subsequent deposition of a thin GaInN layer onto the epitaxial laterally overgrown GaN. The critical thickness for the formation of pits depended upon the concentration of In in GaInN and upon the Burgers vector. It was demonstrated that electron back-scattering diffraction pattern analyses could estimate the 2-dimensional distribution of the c-axis orientation of epitaxial laterally overgrown GaN, for wide areas, with an accuracy of 0.2° or better.

Electron Microscopy Analyses of Microstructures in ELO-GaN. N.Kuwano, K.Horibuchi, K.Kagawa, S.Nishimoto, M.Sueyoshi: Journal of Crystal Growth, 2002, 237-239[2], 1047-54