Growth of ZnO nanorods on fluorine-doped tin oxide substrate without catalyst by radio-frequency magnetron sputtering

•ZnO nanorods were grown on FTO-coated glass by rf magnetron sputtering.•Temperature and type of the substrates strongly affected the ZnO nanorod growth.•New mechanism for ZnO nanorod growth was proposed.

ZnO nanorods were directly grown on fluorine-doped tin oxide (FTO)-coated glass substrate by radio frequency magnetron sputtering without a buffer layer or a catalyst. The deposition time, substrate temperature, and type of substrate were varied to investigate the growth behavior of ZnO nanorods. At an early stage of growth, nano-sized particles were locally formed on the faceted surface of FTO, which were finally grown into the nanorods. The substrate temperature of over 400 °C was required for ZnO nanorod growth. ZnO nanorods were well grown on FTO, SnO2-coated Si, and SnO2-coated SiO2 substrates whereas ZnO thin film was deposited on Cu foil, stainless steel, Au-coated SiO2, and Pt-coated SiO2 substrates. Based on the obtained results, a growth mechanism for ZnO nanorods was proposed.