Study of nanocrystal TiO2 thin films by thermal annealing |
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Authors: | Z W Zhao B K Tay |
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Affiliation: | (1) School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798 |
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Abstract: | The amorphous films were annealed in a wide temperature range (250–1000∘C) and film properties of TiO2 thin films were studied. Nano-sized anatase polycrystallites had been induced by thermal annealing for the films annealed
at and above 300∘C as confirmed by X-ray diffraction. Strong LO-phonon Raman modes, especially B1g
(395 cm−1) and E
g
(636 cm−1) in Raman spectra and the absorption peak at 436 cm−1 in absorbance spectra by Fourier transform infrared spectroscopy also indicated the existence of anatase phase in crystalline
thin films. In addition, with the increase of the annealing temperature, the wettability of the film surface was enhanced
as shown by the decrease of water contact angle from over 90∘ to less than 40∘. Moreover, upon UV laser irradiation on film surface, the water contact angle saturated at 10∘ indicative of a highly hydrophilic surface for all the films, which arose from the dissociative adsorption of water molecules
on the defect sits of the surface generated by the photocatalysis reactions of TiO2. This behavior makes the film a good potential candidate for self-clean coatings. |
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Keywords: | Anatase Raman scattering FTIR photocatalysis |
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