Spectroscopic ellipsometrical studies of UV irradiation effects on the surface properties of the ultra thin native oxide film on titanium

Under ultraviolet (UV) irradiation, an ultra thin titanium native oxides film covered by a hydrocarbon contamination (HC) layer on the as-deposited titanium film was investigated by using spectroscopic ellipsometry (SE), atomic force microscopy (AFM) and contact angle meter. Using a stable silicon dioxide sample as a reference provided an insight of the structural change of the titanium native oxide film under UV irradiation. The SE results indicate that UV irradiation can completely remove the adsorbed HC layer both on the Ti sample and on Si sample after 337 min and 4059 min respectively. The titanium native oxide accelerates the HC removing process. The pseudo-optical constants (pseudo-n and pseudo-k) of the Ti composite and the thickness of the surface layer on Ti decreased during UV irradiation, which was considered to be contributed to the changes of the surface properties of the titanium composite film. AFM images on the surface of UV-treated titanium native oxide films present a less root-mean-square (RMS) roughness and many isolated gains with a size of about 10 nm.