Formation of vertically aligned ZnO nanorods on ZnO templates with the preferred orientation through thermal evaporation

Vertically aligned ZnO nanorods were successfully synthesized on Si substrates at 700 °C through the conventional thermal evaporation method using a ZnO template of thin films instead of metal catalysts. The ZnO nanorods on the ZnO film show a high quality, a large-scale production, and a vertical alignment along the [0 0 1]_ZnO. The origin of the vertical alignment is ascribed to the preferred orientation of the ZnO template, in which most of the (0 0 2) planes are parallel to the ZnO/Si interface. Moreover, the XRD profile shows that the ZnO films play the role of a template layer to fabricate the vertically aligned ZnO nanorods. In addition, this process is cost-effective compared to the thin-film growth system and overcomes the problem of impurity incorporation using metal catalysts.