Using c-oriented ZnO film prepared by spin-coating method as buffer layer

ZnO nanostructures were controllablely synthesized via electrochemical route.The well-aligned ZnO nanorod（about 50 nm in diameter） arrays with the density of 2.5×107 mm-2 were obtained under the unchanged synthesis current density condition.By changing properly the synthesis current density（increasing or decreasing gradually） during growth process

we obtained the vertically ZnO nanorod arrays with the changed diameter（thin or thicken gradually）

that is

realizing the controllable growth of the morphology and dimension of ZnO nanorods.The c-oriented ZnO buffer layer not only supplies the nucleating centers for well-aligned growth

but also reduces significantly the lattice mismatch between Si substrate and ZnO.PL results indicate that the ZnO nanorod arrays samples with ZnO buffer layer have much stronger ultraviolet emission and weaker visible emission as compared to the sample without ZnO buffer layer

showing the important action of ZnO buffer layer on obtaining excellent ZnO crystal quality.