Crystals which were 2 to 3mm in length, and 0.8 to 1mm in width, were grown by using the sublimation technique. Atomic force microscopy was used to analyze the surface morphology of as-grown specimens. It was found that, in free-standing bulk single crystals, 2-dimensional growth was dominated by a step-growth mechanism. However, in the case of preparation via sublimation, spiral growth which originated from screw dislocations predominated.

Surface Morphology Studies on Sublimation Grown GaN by Atomic Force Microscopy. R.S.Q.Fareed, S.Tottori, K.Nishino, S.Sakai: Journal of Crystal Growth, 1999, 200[3-4], 348-52