Phase-segregation assisted growth of quasi-aligned ZnO nanorods on a Mg0.6Zn0.4O-coated Si substrate by thermal evaporation

Vertically aligned ZnO nanorods were synthesized on a lattice-mismatched cubic-phase Mg0.6Zn0.4O thin-film-coated Si substrate through thermal evaporation of the mixture of carbon and ZnO powders in Ar flow with an atmospheric pressure. X-ray diffraction (XRD) and Raman scattering spectrum results confirmed that the ZnO nanorods have a wurtzite structure. Transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and high-resolution TEM (HRTEM) studies indicated that the nanorods grow along the [0001] orientation. The room-temperature photoluminescence of a strong ultraviolet (UV) emission at 379 nm and a very weak deep-level emission at 510 nm implied the high optical quality of ZnO nanorods. The influence of growth time and substrate temperature on the morphologies of the nanorods was also investigated. It was found that the growth of ZnO nanorods was assisted by thermally induced phase segregation. A possible growth mechanism is proposed.