Influence of substrate and annealing temperatures on optical properties of RF-sputtered TiO 2 thin films
TiO 2 thin films were deposited on unheated and heated glass substrates at an elevated sputtering pressure of 3 Pa by radio frequency (RF) reactive magnetron sputtering. TiO 2 films deposited at room temperature were annealed in air for 1 h at various temperatures ranging from 300 to 600 °C. The st...
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| Main Authors: | , , , , |
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| Format: | Article |
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Optical Materials
2010
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| Subjects: | |
| Online Access: | http://ac.els-cdn.com/S092534670900216X/1-s2.0-S092534670900216X-main.pdf?_tid=64b518a8-4024-11e2-b8de-00000aacb35d&acdnat=1354853762_3b99b598d7703c25f91263267c0c8afb http://ac.els-cdn.com/S092534670900216X/1-s2.0-S092534670900216X-main.pdf?_tid=64b518a8-4024-11e2-b8de-00000aacb35d&acdnat=1354853762_3b99b598d7703c25f91263267c0c8afb |
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| Summary: | TiO 2 thin films were deposited on unheated and heated glass substrates at an elevated sputtering pressure of 3 Pa by radio frequency (RF) reactive magnetron sputtering. TiO 2 films deposited at room temperature were annealed in air for 1 h at various temperatures ranging from 300 to 600 °C. The structural and optical properties of the thin films were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible-near infrared (UV-VIS-NIR) spectrophotometry. XRD results show that as-grown and post-annealed TiO 2 films have anatase crystal structure. Higher substrate and annealing temperatures result in a slight increase of crystallinity. TiO 2 films deposited at different substrate temperatures exhibit high visible transmittance and the transmittance decreases slightly with an increase in annealing temperature. The refractive indices (at λ = 550 nm) of the as-deposited and annealed films are found to be in the range of 2.31-2.37 and 2.31-2.35, respectively. Extinction coefficient decreases slightly with increasing substrate and annealing temperatures. The indirect and direct optical band gap of the as-grown films increases from 3.39 to 3.42 eV and 3.68 to 3.70 eV, respectively, with the increase of substrate temperatures. Annealed TiO 2 films also exhibit an increase in the values of indirect and direct optical band gap. |
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