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Compositional Tailored Sol-Gel SiO2–TiO2 Thin Films: Crystallization, Chemical Bonding Configuration, and Optical Properties

Published online by Cambridge University Press:  03 March 2011

Li-Lan Yang ,
Yi-Sheng Lai ,
J.S. Chen ,
P.H. Tsai ,
C.L. Chen  and
C. Jason Chang
Li-Lan Yang
Affiliation:
Department of Materials Science and Engineering, National Cheng Kung University,Tainan, Taiwan, People’s Republic of China
Yi-Sheng Lai
Affiliation:
Department of Materials Science and Engineering, National Cheng Kung University,Tainan, Taiwan, People’s Republic of China
J.S. Chen
Affiliation:
Department of Materials Science and Engineering, National Cheng Kung University,Tainan, Taiwan, People’s Republic of China
P.H. Tsai
Affiliation:
Electronics Research & Service Organization, Industrial Technology Research Institute,Hsinchu, Taiwan, People’s Republic of China
C.L. Chen
Affiliation:
Electronics Research & Service Organization, Industrial Technology Research Institute,Hsinchu, Taiwan, People’s Republic of China
C. Jason Chang
Affiliation:
Electronics Research & Service Organization, Industrial Technology Research Institute,Hsinchu, Taiwan, People’s Republic of China
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Abstract

Thin films of SiO2–TiO2 composite oxides with various SiO2:TiO2 compositions were prepared by the sol-gel method, using tetraethylorthosilicate (TEOS) and titanium tetraisopropoxide (TTIP) as precursors. The composition, crystal structure, and chemical bonding configuration of the as-deposited and annealed SiO2–TiO2 thin films were analyzed using Rutherford backscattering spectrometry (RBS), glancing incident angle x-ray diffraction (GIAXRD) and Fourier transform infrared spectroscopy (FTIR), respectively. Optical properties of the films were characterized by spectroscopic ellipsometry and ultraviolet-visible spectrophotometry. The Si/Ti ratios in the SiO2–TiO2 films agree with the TEOS/TTIP molar ratio in the sol-gel precursor. When the TEOS/(TEOS + TTIP) ratio is greater than 40%, the SiO2–TiO2 thin films remain amorphous (without formation of TiO2 crystalline phase) after annealing at temperatures as high as 700 °C. FTIR spectra indicate that the quantity of Si–O–Ti bonding can be maximized when the TEOS:TTIP in the precursor is 80%:20%. The refractive index of the SiO2–TiO2 films increases approximately linearly to the mixing ratio of TTIP/(TEOS + TTIP). However, SiO2-rich films possess higher ultraviolet-visible transmittance than the TiO2-rich films. The modification of microstructure and chemical bonding configuration in the SiO2–TiO2 films by the composition and its influence on the optical properties are discussed.

Keywords

Optical propertiesSol-gelThin film
Type
Articles
Information
Journal of Materials Research , Volume 20 , Issue 11 , November 2005 , pp. 3141 - 3149
Copyright
Copyright © Materials Research Society 2005

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