Electrical characteristics of rf-magnetron sputtered BaTa₂O₆ thin film

The characteristics of radio-frequency magnetron sputtered BaTa₂O₆ thin films with aluminum (Al) top and indium tin oxide (ITO) bottom electrodes have been investigated as a function of applied field and temperature. The optical transmittance in the visible range was in range of 80-90% regardless of the substrate temperature. The dielectric constant increased from 20 to 30 with increasing the substrate temperature and nearly independent of the frequency in the range of 0.3-100 kHz but the loss factors increased with increasing the substrate temperature at high frequency. The leakage currents of BaTa₂O₆ thin film are in the order of 10^-6-10^-7 A/cm² at the applied field of 1 MV/cm and the charge storage capacitance (εE_breakdown) are 5.64 (100°C), 10.6 (200°C) and 11.8 (300°C) μC/cm². From the deposition temperature, voltage polarity and thickness dependence of leakage current, we can conclude that the dominant conduction mechanism is ascribed to Schottky emission at high electric field (> 1 MV/cm) and hopping conduction at low electric field (< 1 MV/cm). The Schottky barrier heights measured are 1.14 eV at Al(+) and 0.8 eV at Al(-).