Structure and Optical Properties of SrTiO3 Thin Films Prepared by a Sol–Gel Technique

Abstract

Transparent and crack-free SrTiO3 thin films were prepared on fused silica substrates by a sol–gel technique. Strontium acetate and titanium tetra-n-butoxide were used as starting materials. The structural properties of the thin films were studied by X-ray diffraction. The films annealed at 700 °C have good crystallinity. The optical transmission properties of the thin films were measured in the wavelength range 200 to 1100 nm. The thin films possess high optical transmission. By using an approximate formula, the refractive index and the band gap were evaluated. The dispersion relation follows the single electron oscillation model. The band gap of well-crystallized film is comparable to that of single crystal reported. However, for poor-crystallized films, their band gap values are much larger than of single crystal. The larger gap shift is believed to be mainly due to both quantum size effect and amorphous phase effect.