Study of the dielectric and ferroelectric properties of chemically processed Ba xSr 1− xTiO 3 thin films

Abstract

Polycrystalline Ba x Sr 1− x TiO 3 ( x=0.4 and 0.8) thin films with a perovskite structure were prepared by the polymeric precursor method on a platinum-coated silicon substrate. High-quality thin films with uniform composition and thickness were successfully produced by dip-coating and spin-coating techniques. The resulting thin films prepared by dip and spin-coating showed a well-developed dense polycrystalline structure with uniform grain size distribution. The metal–BST-metal structure of the thin films displays good dielectric and ferroelectric properties. The ferroelectric nature to Ba x Sr 1− x TiO 3 ( x=0.8) thin film, indicated by butterfly-shaped C– V curves and confirmed by the hysteresis curve, showed 2 P r=5.0 μC/cm 2 and E c=20 kV/cm. The capacitance–frequency curve reveals that the dielectric constant may reach a value of up to 794 at 1 kHz. On the other hand, the Ba x Sr 1− x TiO 3 ( x=0.4) thin films had paraelectric nature and dielectric constant and the dissipation factor at a frequency of 100 kHz were 680 and 0.01, respectively, for film annealed at 700°C. In addition, an examination of the film's I–V curve at room temperature revealed the presence of two conduction regions in the Ba x Sr 1− x TiO 3 ( x=0.4 and 0.8) thin films, showing ohmic-like behavior at low voltage and a Schottky-emission or Poole–Frenkel mechanism at high voltage.