Growth of well-aligned ZnO nanowire arrays on Si substrate

Well-aligned ZnO nanowire arrays have been successfully synthesized on Si( 100) substrate by a vapour transport process. A ZnO thin film was used as the nucleation sites, which can control the growth orientation of the nanowires. By observation of the initial process of nanowire growth, a vapour transport solid condensation mechanism was proposed for ZnO nanowire growth, in which the role of ZnO thin film was to provide nucleation sites for nanowire growth. It was also found that the nanowire density could be adjusted by varying the thickness of the ZnO thin film. The synthesized ZnO nanowires, which had a single-crystalline wurtzite structure, had diameters of 50-120 nm and lengths of around 5 mu m. The strong ultraviolet emission and weak deep level emission reflect the high optical quality of the nanowires.