EFFECT OF THE OXYGEN ADDITION IN THE SPUTTERING GAS ON THE DIELECTRIC PROPERTIES OF a-BaTiO3 FILMS

Amorphous barium titanate films (a-BTO) were grown by the RF magnetron sputtering technique at low temperature and under various oxygen/argon mixing ratios (OMR). Their dielectric properties (dielectric constant, loss and ac conductivity in the 0.1–105 Hz range), dc leakage currents, and thermally stimulated currents were systematically studied as a function of OMR in the sputtering gas (0% to 20 %). We demonstrate that the presence of oxygen plays a significant role in improving the dielectric properties of a-BTO thin films. The oxygen incorporation successfully suppressed some electrical defects. The bulk conductivity and leakage currents are reduced although a small decrease of dielectric constant has been observed. Films prepared at higher oxygen ratio (20%) have a small leakage current density (3.6 × 10− 7 A/m2) and lower tangent loss (2 × 10− 3).