Solvothermally grown ZnO nanorod arrays on (101) and (002) single- and poly-crystalline Zn metal substrates

One-dimensional (1D) ZnO nanorod (NR) arrays were grown on (101) and (002) single- and poly-crystalline Zn substrates via direct surface-oxidation in solution, i.e. solvothermal method. The surface-oxidation was done in a solvent mixture of water and 1-propanol with the optimum pH adjusted by adding ammonia. X-ray diffraction patterns revealed that the ZnO NRs grown on the Zn substrates were of single-crystalline with wurtzite structure. The ZnO NRs grown on the (002) single- and poly-crystalline substrates grew in the <001> direction, in contrast to the NRs grown on the (101) single-crystal substrate which were oriented predominantly in the <101> direction. The texture coefficient of the grown ZnO NRs was calculated from the XRD data. Well-aligned NRs that had tips of various shapes were examined by scanning electron microscopy and transmission electron microscopy techniques. The optical properties of the ZnO NRs grown on the Zn substrates were characterized by photoluminescence (PL) spectroscopy.