Pit arrays forming a network structure were observed by atomic force microscopy on an AlGaN surface of an AlGaN/GaN heterostructure on a Si(111) substrate. In order to clarify the origin of these pit arrays, AlGaN/GaN layers were investigated by using transmission electron microscopy. As a result, it was confirmed that pit arrays on the surface, observed by atomic force microscopy, represented the surface termination of edge dislocations formed at the small-angle boundaries of slightly misoriented crystal domains. The difference in buffer layer structures formed on Si substrates affected the surface pit arrangement. It was also confirmed that the optimization of a buffer structure on a Si substrate was very effective for the reduction of the pit density.

Investigation of Surface Defect Structure Originating in Dislocations in AlGaN/GaN Epitaxial Layer Grown on a Si Substrate. H.Sasaki, S.Kato, T.Matsuda, Y.Sato, M.Iwami, S.Yoshida: Journal of Crystal Growth, 2007, 298, 305- 9

Figure 1

Diffusion Length of Ga on the (00▪1) Facet of AlGaN