Formation of ZnO nanowires during short durations of potentiostatic and galvanostatic anodization

• Anodization mode controls the nucleation and growth of nanowires on a Zn foil.
• The growth rate of nanowires is 0.04 μm/s for both modes.
• Galvanostatic mode is suitable for anodization of the sputtered thin Zn film.

Different behaviors during the formation of ZnO nanowires from a Zn foil by either potentiostatic or galvanostatic anodization are described herein. During the initial stage, 4.5 fold fewer nucleation sites are created in potentiostatic mode than galvanostatic mode. However, the nucleation sites continuously increase as anodization proceeds in the potentiostatic mode, whereas the number of nucleation sites is determined at the beginning of anodization in galvanostatic mode. Overall, the total number of nanowires produced is almost identical. The growth rate of nanowires is 0.04 μm/s for both modes. Based on the findings during anodization of a Zn foil, a sputtered film of Zn is anodized. In galvanostatic mode, the growth of well-defined nanowires is similar to that observed during anodization of the foil, whereas sparse growth of nanowire bundles is observed in potentiostatic mode. The formation of unevenly grown nanowires is ascribed to the surplus growth species, which are intensively deposited on a few nucleation sites.