Investigation of surface pits originating in dislocations in AlGaN/GaN epitaxial layer grown on Si substrate with buffer layer

An AlGaN/GaN heterostructural layer with a crack-free smooth surface was grown on multiple buffer layers formed on a Si(111) substrate. On the AlGaN surface, pit arrays forming a network structure were observed by atomic force microscopy (AFM). In order to clarify the origin of these pit arrays, the AlGaN/GaN layer was investigated using transmission electron microscopy (TEM). As a result, similar network structures of threading edge dislocations in the AlGaN/GaN layer were observed by plan-view TEM. It was thus confirmed that the surface pit arrays observed by AFM represent the surface termination of edge dislocations formed at the small-angle boundaries of slightly misoriented crystal domains.