Characterization of size-controlled ZnO nanorods produced by electrochemical deposition technique

ZnO nanorods have been grown onto Indium thin Oxide (ITO) coated glass substrates by electrochemical deposition technique using ZnCl₂ (0.005 M), KCl (0.1 M), solutions at the bath temperature of 80°C and 5.8 pH value. The seed layers were pre-deposited galvanostatically applying different currents such as -1.0 mA and -2.0 mA and the subsequent ZnO nanorods had been produced using the potentiostatic mode at the potential of -1.0 V. Energy band gaps of ZnO nanorods which were produced using the seed layers at the currents of -1.0 mA and -2.0 mA were 3.52, and 3.60 eV, respectively. On the other hand, the Energy band gap of ZnO nanorods which were produced without using seed layers at the potential of -1.0 V was 3.50 eV. The structure and the surface morphology of ZnO nanorods were studied by x-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). X-ray diffraction results showed that the preferred crystallographic orientation of ZnO nanorods is in the <;0002>; direction. AFM results have shown that surface roughnesses of ZnO nanorods with seed layers at the currents of -1.0 mA and -2.0 mA were 272, and 126 nm, respectively. AFM results also have sown that the surface roughness of ZnO nanorods which were produced without the seed layer was 226 nm. Diameters of hexagons of ZnO nanorods produced with seed layers at the currents of -2.0 and -1.0 mA were determined as 350, and 470 nm, respectively. The diameter of hexagons of ZnO nanorods produced without seed layers was determined as 550 nm from AFM images. The SEM images have shown that the lengths of the ZnO nanorods varied between 1.0 and 2.5 μm.