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A Spectroscopic Ellipsometry Study of TiO2 Thin Films Prepared by dc Reactive Magnetron Sputtering: Annealing Temperature Effect |
| Mati Horprathum1;Pongpan Chindaudom2;Pichet Limsuwan1 |
| 1Department of Physics, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand2Optical Coating Laboratory, National Electronics and Computer Technology Center, Pathumthani 12120, Thailand |
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| Cite this article: |
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Mati Horprathum, Pongpan Chindaudom, Pichet Limsuwan 2007 Chin. Phys. Lett. 24 1505-1508 |
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Abstract TiO2 thin films are obtained by dc reactive magnetron sputtering. A target of titanium (99.995%) and a mixture of argon and oxygen gases are used to deposit TiO2 films on to silicon wafers (100). The crystalline structure of deposited and annealed film are deduced by variable-angle spectroscopic ellipsometry (VASE) and supported by x-ray diffractometry. The optical properties of the films are examined by VASE. Measurements of ellipsometry are performed in the spectral range 0.72--3.55eV at incident angle 75°. Several SE models, categorized by physical and optical models, are proposed based on the `simpler better' rule and curve-fits, which are generated and
compared to the experimental data using the regression analysis. It has been found that the triple-layer physical model together with the Cody--Lorentz dispersion model offer the most convincing result. The as-deposited films are found to be inhomogeneous and amorphous, whereas the annealed films present the phase transition to anatase and rutile structures. The refractive index of TiO2 thin films increases with annealing temperature. A more detailed analysis further reveals that thickness of the top sub-layer increases, whereas the region of the bottom amorphous sub-layer shrinks when the films are annealed at 300°C.
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| Keywords:
07.60.Fs
78.20.-e
81.15.Cd
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Received: 20 February 2007
Published: 17 May 2007
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| PACS: |
07.60.Fs
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(Polarimeters and ellipsometers)
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78.20.-e
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(Optical properties of bulk materials and thin films)
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81.15.Cd
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(Deposition by sputtering)
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