The dislocation arrangements, in films which had been prepared by lateral epitaxial overgrowth, were studied by means of cathodoluminescence mapping and transmission electron microscopy. A very low (less than 10-6/cm2) density of electrically active defects was found in laterally overgrown material. Individual electrically active defects were observed that propagated laterally, from the line of stripe coalescence, into the overgrown material. These defects were shown to be limited to the underlying material, and did not propagate normal to the surface, as in other GaN films. In the seed region, the threading dislocation image-widths were seen to be nearly identical in the quantum well and in the underlying GaN. It was shown that, by varying the processing conditions, these lateral defects could be avoided in lateral epitaxial overgrown films.

Cathodoluminescence Mapping of Epitaxial Lateral Overgrowth in Gallium Nitride. S.J.Rosner, G.Girolami, H.Marchand, P.T.Fini, J.P.Ibbetson, L.Zhao, S.Keller, U.K.Mishra, S.P.DenBaars, J.S.Speck: Applied Physics Letters, 1999, 74[14], 2035-7