Effect of oxygen to argon ratio on defects and electrical conductivities in Ba_0.47Sr_0.53TiO₃thin-film capacitors

Abstract

The ionic and electronic conductivity characteristics and defects in the Ba0.47Sr0.53TiO3 (BST) thin films that were rf-sputtered at 450 °C on a Pt bottom electrode at various O2/(Ar+O2) mixing ratios (OMR) were studied. The dielectric properties specific to the BST films can be explained by considering the influence of the dielectric relaxation phenomenon. Through the measurement of the dielectric dispersion as a function of frequency (100 Hz f10 MHz) and temperature (27 °C T150 °C), we studied the dielectric relaxation and obtained the defect quantity of the films, on the basis of the capacitance, admittance and impedance spectra. The defect density of BST films decreases with an increase of OMR. The majority of electrical conductivity is carried by electrons (electronic conductivity) and not the ionic defects (ionic conductivity).