Selective growth of pure and long ZnO nanowires by controlled vapor concentration gradients

ZnO can appear as nanowires, nanobelts, and nanocombs, which are attractive for various applications. However, this has prevented the growth of desired nanostructures without other trace morphologies. Here we demonstrated a mechanism for selective growth of pure and long ZnO nanowires. This was obtained by placing a gold film at a high-temperature zone so that ZnO nanowires with controllable densities can be grown on adjacent bare substrates at lower temperature zones. The concentration gradients of gold and ZnO vapors are responsible for this selective growth, which could be applicable for selective growth of ZnO nanobelts and nanocombs in the future.