Surface chemistry modification in ITO films induced by Sn²⁺ ionic state variation

In this study, the surface-chemistry-dependent hydrophobicity and antibacterial properties of ITO films were examined. After annealing of the films, their surface root-mean-square roughness increased and remained the same regardless of the annealing environment. However, depending on the annealing environment (O₂, N₂, Ar, or vacuum), the contact angle increased with increasing Sn²⁺ contents in the films. Furthermore, the antibacterial effect of the annealed films decreased regardless of the annealing environment. The depth-dependent chemical state determined by X-ray photoelectron spectroscopy showed an increase in the Sn content at the surfaces of all films. In particular, the as-grown film exhibited the highest Sn content at the surface and also the strongest antibacterial effect.