Non-polar a-plane (11•0) GaN films were grown on r-plane (1¯1•2) sapphire substrates by metal organic chemical vapour deposition. The influences of V/III ratio on the species diffusion anisotropy of a-plane GaN films were investigated by scanning electron microscopy, cathodoluminescence and high-resolution X-ray diffraction measurements. The anisotropy of a-plane GaN films might result from the different migration length of adatoms along two in-plane directions. The V/III ratio had an effect on the growth rates of different facets and crystal quality. The stripe feature morphology was obviously observed in the film with a high V/III ratio because of the slow growth rate along the [1¯1•0] direction. When the V/III ratio increased from 1000 to 6000, the in-plane crystal quality anisotropy was decreased due to the weakened predominance in migration length of gallium adatoms.

Effects of V/III Ratio on Species Diffusion Anisotropy in the MOCVD Growth of Non-Polar a-Plane GaN Films. L.B.Zhao, T.J.Yu, J.J.Wu, Z.J.Yang, G.Y.Zhang: Chinese Physics B, 2010, 19[1], 018101