An atomic force microscopic study was made of linear dislocations and surface defects in p-type and n-type metalorganic chemical vapor deposited, hydride vapor phase epitaxial, and molecular beam epitaxial films on sapphire. It was found that the surface pits due to threading dislocations were not distributed randomly, but on the boundaries of growth columns. The dislocations were thought to be electrically active since the average distance between them (average column size) was comparable to the minority carrier diffusion lengths. The diffusion lengths for holes and electrons were of the same order as the sizes of regions which were free from surface dislocations.

Correlation between the Surface Defect Distribution and Minority Carrier Transport Properties of GaN. P.M.Bridger, Z.Z.Bandić, E.C.Piquette, T.C.McGill: Applied Physics Letters, 1998, 73[23], 3438-41