Phase dependent growth of superficial nanowalls-like structure on TiO2 thin films in molecular hydrogen (H2) annealing environment |
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Authors: | M. Saleem M.F. Al-Kuhaili S.M.A. Durrani I.A. Bakhtiari |
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Affiliation: | 1. Preparatory Year Program – Physical Science, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia;2. Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia |
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Abstract: | We report the surface modification and growth of nanostructures on the surface of titanium oxide thin films during post deposition annealing in molecular hydrogen ambient. Titanium oxide thin films of a thickness of 200 nm were deposited by electron-beam evaporation at a substrate temperature of 300 °C. Films were annealed in 50 and 100 sccm flow rates of hydrogen in the temperature range of 200 °C–600 °C for 4 h. X-ray diffraction analysis showed a polycrystalline structure of the films. Anatase-to-rutile phase transformation took place, and was influenced by the hydrogen flow rate. Atomic force microscopy indicated the growth of 4–6 μm domains enclosed by nanowalls-like boundaries on the surface when the rutile phase was formed. Spectrophotometer measurements indicated that the films were transparent and a red shift in absorption edge was observed due to annealing. The direct band gaps of anatase and rutile were found to be 3.5 eV and 3.2 eV, respectively. |
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Keywords: | TiO2 thin films Electron-beam evaporation Hydrogen annealing Nanowalls Microdomains |
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