A reduction in extended-defect densities in a-plane (11▪0) GaN films was achieved via lateral epitaxial overgrowth by hydride vapor phase-epitaxy. A variety of dielectric mask patterns was used to produce 8 to 125µm thick fully coalesced non-polar GaN films. The nm-scale pit densities in the overgrown regions were less than 3 x 106/cm2; as compared with ~1010/cm2 in the direct-growth a-plane GaN. Cathodoluminescence revealed a fourfold increase in luminous intensity in the overgrown material as compared to the window material. The X-ray rocking curves indicated that the films were free of wing tilt within the sensitivity of the measurements. Whereas non-lateral epitaxial overgrown a-plane GaN exhibited basal-plane stacking fault and threading dislocation densities of 105/cm and 109/cm2, respectively, the overgrown lateral epitaxial material was essentially free of extended defects. The basal-plane stacking fault and threading dislocation densities in the wing regions were below the detection limits of ~5 x 106/cm2 and 3 x 103/cm, respectively.

Defect Reduction in (11¯20) a-Plane Gallium Nitride via Lateral Epitaxial Overgrowth by Hydride Vapor-Phase Epitaxy. B.A.Haskell, F.Wu, M.D.Craven, S.Matsuda, P.T.Fini, T.Fujii, K.Fujito, S.P.DenBaars, J.S.Speck, S.Nakamura: Applied Physics Letters, 2003, 83[4], 644-6