Control of cathodic potential for deposition of ZnO by constant-current electrochemical method

For the preparation of functional films and crystals, the electrochemical deposition method has advantages of large-area deposition at low temperature and high efficiency in terms of the raw materials used. However, crystallization through electrochemical processes is not currently well understood. To apply the electrochemical deposition method, it is necessary to better understand the crystallization and the growth mechanism. To investigate the mechanism, it is essential to ensure the reproducibility of the growth process. We focused on cathodic potential as a parameter that affects the reproducibility of the galvanostatic method. The repeatability of cathodic potentials during deposition was drastically improved by optimizing the mask pattern on the electrode and the pre-treatment conditions. As the result, the cathodic potential was able to be controlled by the current density. Furthermore, nucleation and grain growth of ZnO crystals by the galvanostatic electrochemical method are discussed in association with the change of cathodic potential. Changes in grain size at various cathodic currents are also discussed.