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.