The crystal quality of a-plane GaN films was improved by using epitaxial lateral overgrowth on a nanorod GaN template. The investigation of X-ray diffraction showed that the strain in a-plane GaN grown on r-plane sapphire could be mitigated. The average threading dislocation density estimated by transmission electron microscopy was reduced from 3 x 1010 to 3.5 x 108/cm2. From the temperature-dependent photoluminescence, the quantum efficiency of the a-plane GaN was enhanced by the nanorod epitaxial lateral overgrowth. These results demonstrated the opportunity of achieving a-plane GaN films with low dislocation density and high crystal quality via nanorod epitaxial lateral overgrowth.

Nanorod Epitaxial Lateral Overgrowth of a-Plane GaN with Low Dislocation Density. S.C.Ling, C.L.Chao, J.R.Chen, P.C.Liu, T.S.Ko, T.C.Lu, H.C.Kuo, S.C.Wang, S.J.Cheng, J.D.Tsay: Applied Physics Letters, 2009, 94[25], 251912