Effect of oxygen to argon ratio on defects and electrical conductivities in Ba0.47Sr0.53TiO3 thin-film capacitors

The ionic and electronic conductivity characteristics and defects in the Ba 0.47Sr0.53TiO3 (BST) thin films that were rf-sputtered at 450 degrees C on a Pt bottom electrode at various O-2/(Ar + O-2) mixing ratios (OMR) were st udied. The dielectric properties specific to the BST films can be explained by considering the influence of the dielectric relaxation phenomenon. Thro ugh the measurement of the dielectric dispersion as a function of frequency (100 Hz less than or equal to f less than or equal to 10 MHz) and temperat ure (27 degrees C less than or equal to T less than or equal to 150 degrees C), we studied the dielectric relaxation and obtained the defect quantity of the films, on the basis of the capacitance, admittance and impedance spe ctra. The defect density of BST films decreases with an increase of OMR. Th e majority of electrical conductivity is carried by electrons (electronic c onductivity) and not the ionic defects (ionic conductivity).