Growth and green defect emission of ZnPbO nanorods by a catalyst-assisted thermal evaporation-oxidation method

Vertically aligned undoped and Pb-doped ZnO (ZnPbO) nanorods have been successfully synthesized by a thermal evaporation-oxidation method with the Fe-based catalysts on sapphire substrate at different temperatures (600-700 °C) for 2 h. Effects of growth temperature and Pb-doping on the morphology, structure, and optical properties of as deposited nanorods have been investigated. The products at 600-700 °C showed a 1D nanorod morphology with an average diameter in the range 450-150 nm, and length in the range 3-6 μm. Well-aligned, uniform and elongated nanorods were obtained at 700 °C. The photoluminescence (PL) spectra showed that undoped ZnO nanorods exhibited a strong and sharp ultraviolet (UV) band edge emission peak at 380 nm (3.26 eV), whereas Pb-doped ZnO nanorod arrays exhibited a relative weak ultraviolet (UV) emission at 380 nm and a strong green emission at 515 nm (2.41 eV). A mechanism for the nanorod growth and defect emission is proposed.