Plasma-Assisted Chemical Vapor Deposition of TiO₂ Thin Films for Highly Hydrophilic Performance

Satoshi Yamauchi, Yoh Imai

Department of Biomolecular Functional Engineering, Ibaraki University, Hitachi, Japan.
Department of Electric and Electronic Engineering, Ibaraki University, Hitachi, Japan.

DOI: 10.4236/csta.2013.21001                

Abstract

Titanium-oxide layer was grown on glass substrate by plasma-assisted chemical vapor deposition (PCVD) using oxygen gas plasma excited by radio-frequency power at 13.56 MHz in the pressure as low as 3mtorr at relatively low temperature below 400^oC, and studied on the crystallographic properties with the hydrophilic behavior comparing to the layer deposited by low-pressure chemical vapor deposition (LPCVD). Raman spectra indicated anatase-phase TiO₂ layer without amorphous-phase could be formed above 340^oC by simultaneous supply of plasma-cracked and non-cracked titanium-tetra-iso-propoxide (TTIP) used as preliminary precursor. Surface Scanning Electron Microscope images indicated the PCVD-layer consists of distinct nanometer-size plate-like columnar grains, in contrast to rugged micrometer-size grains in the LPCVD-layer. Extremely small water contact angle about 5^o in dark and the quick conversion to super-hydrophilicity by UV-irradiation with a light-power density as low as 50 W/cm² were observed on the PCVD- layer grown at 380^oC, while the large initial contact angle was above 40^o and the response for the UV-irradiation was gradual on the LPCVD-layer.

Keywords

PCVD; Titanium-Oxide Films; Anatase-TiO₂; Hydrophilicity

Conflicts of Interest

The authors declare no conflicts of interest.

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