In situ transmission electron microscopy experiments revealed that dimples formed in hexagonal GaN thin crystals by irradiation of a focused transmission electron microscope beam recovered to flatten the surface under a subsequent electron irradiation with a moderately defocused beam. The electron-stimulated recovery could be attributed neither to knock-on damage nor beam heating effects but to electronically enhanced self-diffusion in the GaN crystals.

Evidence of Electron-Stimulated Self-Diffusion in GaN Crystals. Y.Mera, K.Suzuki, K.Maeda: Physica B, 2003, 340-342, 488-91