Structure and electrical properties of barium strontium titanate thin films directly prepared on bare silicon substrates by chemical solution deposition

Barium strontium titanate (BaxSr1-xTiO3) thin films were directly prepared on bare silicon substrates by chemical solution deposition method. X-ray diffraction analysis showed that the thin films formed perovskite phase without the existence of measurable second phase. Scanning electron microscopy observation confirmed that the thin films had dense structure with fine grains. The dielectric constant and dissipation factor of the thin films on Si substrates measured using the low-resistivity silicon as bottom electrodes were 82 and 1%, respectively, at a frequency of 1 kHz. Meanwhile, the dielectric frequency dispersion was observed which could be explained by using a simple combined capacitor model. In addition, the dielectric constants were found to be strongly dependent on compositions of the thin films, specifically, Ba/Sr ratio and (Ba + Sr)/Ti ratio.