The dislocation etch pits in an as-grown [00▪1] direction sapphire crystal (α-Al2O3) produced by Cz method were investigated by using an environmental scanning electron microscope for the first time. The clear and stable contrast images of triangular, hexagonal, and quadrilateral etch pits were observed, which demonstrated the structural symmetry of sapphire crystal along [00▪1] direction. The dislocation density measured was 105 to 2 x 105/cm2.

Observation of Dislocation Etch Pits in a Sapphire Crystal Grown by Cz Method using Environmental SEM. J.Xiao, S.Yin, M.Shao, X.Zhang: Journal of Crystal Growth, 2004, 266[4], 519-22