Extended defect reduction in material which had been grown by lateral epitaxial overgrowth onto large-area wafers, via low-pressure metalorganic chemical vapor deposition, was characterized by using transmission electron microscopy and atomic force microscopy. The laterally overgrown samples had a rectangular cross-section, with smooth (00•1) and {11•0} facets. The density (less than 5 x 106/cm2) of mixed and pure edge threading dislocations in the samples was reduced by some 3 to 4 orders of magnitude; as compared with bulk nitride (about 1010/cm2). A small number of edge dislocations with line directions that were parallel to the basal plane were generated between the bulk-like overgrown GaN and lateral epitaxial overgrowth regions, as well as at the intersection of adjacent merging overgrown stripes. It was assumed that the edge dislocations were generated in order to accommodate the small misorientation between bulk material and laterally epitaxially overgrown regions.

Microstructure of GaN laterally overgrown by metalorganic chemical vapor deposition H.Marchand, X.H.Wu, J.P.Ibbetson, P.T.Fini, P.Kozodoy, S.Keller, J.S.Speck, S.P.DenBaars, U.K.Mishra: Applied Physics Letters, 1998, 73[6], 747-9