Electrical properties of sol–gel derived MPB 0.37BiScO3–0.63PbTiO3 thin films deposited on iridium oxide electrodes

Abstract

The characterization of sol–gel derived morphotropic phase boundary (MPB) 0.37BiScO₃–0.63PbTiO₃ (BSPT) thin films, deposited on IrO₂/TiO₂/SiO₂/Si and Pt/TiO₂/SiO₂/Si substrates, was performed to identify the influence of the IrO₂electrodes on the film's microstructure and electrical properties. Though the ferroelectric behaviour of both films is similar, with remanent polarization values of 26 µC cm⁻² and 23 µC cm⁻², respectively, for IrO₂ and Pt bottom electroded films, the leakage current density (J_L) at room temperature markedly decreases from > 10⁻⁶ A cm⁻² for BSPT on Pt to the order of ≤ 10⁻⁸ A cm⁻² for BSPT on IrO₂, under the maximum voltage of 4 V (∼80 kV cm⁻¹). The formation of an interface layer between the film and the electrode, as observed by Rutherford Backscattering Spectroscopy, is proposed to have a space charge sink effect and, as a consequence, to account for the improvement of the leakage current behaviour of the IrO₂ electroded films.