Preparation and microstructure properties of Al-doped TiO2–SiO2 gel-glass film

Abstract Al-doped TiO2–SiO2 gel-glass thin films on silicon wafers were prepared using a sol–gel method combined with a multi-layer spin coating technique. The precursor to the glass films was obtained by introducing aluminium nitrate with ethanol solution into the hydrolysis system of tetraethylorthosilicate as a dopant. X-ray photoelectron spectroscopy (XPS) depth profiling analysis of the glass films showed an excellent homogeneity of elemental composition. Titanium ions were indicated to exist in Si–O–Ti hetero-condensation forms. The microstructure of the film was investigated using an atomic force microscope across the crater created by Ar+ beam sputtering. The thickness and the refractive index of the film were estimated by means of the reflect spectra measurement.