Growth process of atomically flat anodic films on titanium under potentiostatical electrochemical treatment in H2SO4 solution

The as-deposited titanium film on silicon wafer was electrochemically treated in potential sweep and potential step modes in 0.1 M H2SO4 solution at 30 °C. Under the anodization conditions of potential sweep and properly modulated cyclic voltammetry (CV), nanoscale grains, step-terrace structure and atomic images were clearly observed on the surface of anodic oxide film on titanium. Under potential step conditions, if the anodization time was short (1 s), no grains could be found on the anodic oxide film surface, even though the potential was high up to 9000 mV. Moreover, whatever potential sweep or potential step mode was performed, sufficient time (low sweep rate means a prolonged anodization time) was needed for the formation of nanoscale grains, atomically flat surface and step-terrace structure on the anodized titanium film.