Dielectric properties of pulsed-laser deposited SrTiO₃ films at microwave frequency ranges

The dielectric constant and loss tangent of SrTiO₃ thin films were characterized under the influence of an applied dc voltage at about 3.64 GHz. The measurement was carried out utilizing a gold resonator with a flip-chip capacitor at cryogenic temperatures, The analysis of the experimentally observed capacitance and quality factor served to give a measure of the dielectric constants and the loss tangents of the SrTiO₃ film at microwave ranges, respectively. A dielectric constant of 830 and a low loss tangent of 6 × 10^-3 at 3.64 GHz were observed at 90 K and 100 V. The dielectric loss decreases as the bias voltage increases. In addition, the quality of the SrTiO₃ film is presented in terms of fractional frequency under the bias voltages and cryogenic temperatures.