Research on fabrication of ZnO films by ultrasonic electrochemical deposition and its mechanism

C-axis oriented ZnO films were fabricated by ultrasonic electrochemical deposition (UED). For comparison, ZnO films were also prepared by conventional electrochemical deposition (CED) in the same condition. X-ray diffraction, scanning electron microscopy and optical spectroscopy were used to analysize the structure, surface morphology and optical properties of the films. The results show that ZnO films deposited by CED have the nano-column shape and c-axis orientation presents maximum when increasing the deposition voltage. Also, the optical transmittance is improved by annealing process. The ZnO films deposited at 1.5 V by UED still show the nano-column shape, but exhibit a better c-axis orientation than those prepared by CEM. However, as the deposition voltage increase to 2.0 V, the films show wheat granular structure. The optical transmittance is hardly influenced by post-annealing in this case.