Influence of growth parameters on texture of ZnO nanorods by using electrochemical deposition at low temperatures

Abstract

One-dimensional zinc oxide (ZnO) nanocrystals with various textures and crystalline structures have been fabricated on indium tin oxide (ITO) substrates by using cathodic electrodeposition at 60–80°C. Five sets of parameter settings that include seed layer density, applied potential, growth temperature, deposition period, and annealing temperature, are found to vary the growth of ZnO nanorod arrays on ITO substrates. The structural transformation of as-grown ZnO nanorods is characterized by X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photon spectroscopy. The preferential textured growth (i.e., c-axis) of electrodeposited ZnO nanorods from aqueous electrolyte shows an increase with increasing deposition potential, growth temperature, deposition period, and annealing temperature. The resulting ZnO nanorods display wurzite crystal structure and the crystalline rods grow preferentially in (002) direction according to a small integral intensity ratio of (101)/(002). The spacing between adjacent lattice fringes is approximately 2.620Å, which is close to the interspacing of d002 plane. The analysis of Arrhenius-type plots provides evidence of a multiple-stage growth mechanism according to different apparent activation energies having the following order: 27.5kJ/mol (period: 5min)<41.8kJ/mol (period: 10min)<46.1kJ/mol (period: 20min) within 60–80°C. The study on the parameters affecting the ZnO texture offers significant benefit for growing the desired morphology of ZnO nanorods on conducting substrates at low temperature.