Solid Au nanoparticles as a catalyst for growing aligned ZnO nanowires: a newunderstanding of the vapour–liquid–solid process

Abstract

X-ray diffraction techniques have been applied to characterizethe Au-catalysed growth of aligned ZnO nanowire arrays on anAlGaN/AlN/Al2O3 substrate. The orientation relationships between the AlN layer, AlGaNlayer, ZnO nanowires and Au particles were determined using x-raytexture analysis. Two orientations of the Au nanoparticles, related by a30° rotation about the sample normal, were observed. The gold lattice parameter of the ZnOnanowire sample was determined to be the same as that of a control sample never exposedto vaporized ZnO, indicating the absence of Zn in the Au catalyst particles. Ourresults indicate that the Au catalyst particles were solid during growth, and thatgrowth proceeded by a surface diffusion process, rather than a bulk diffusionprocess.