Films with a nominal thickness of 0.6 were homo-epitaxially deposited onto a sublimation-grown GaN monocrystalline substrate. An electron-transparent area of 10 x 10 was prepared by means of focused Ga ion-beam machining and was examined by using transmission electron microscopy. In addition to dislocations on the basal plane of the wurtzite unit cell, another type of dislocation which was nearly pure edge in character and which was aligned close to the c-axis direction, was found in the GaN substrate crystals. Neither type of dislocation threaded to the top surface. Dislocation-free growth could be obtained in the GaN homo-epitaxial films.

T.Okada, S.Kurai, Y.Naoi, K.Nishino, F.Inoko, S.Sakai: Japanese Journal of Applied Physics, 1996, 35[2-10B], L1318-20