Reduced dielectric loss and leakage current in CaCu3Ti4O12/SiO2/CaCu3Ti4O12 multilayered films

The CaCu3Ti4O12/SiO2/CaCu3Ti4O12 (CCTO/SiO2/CCTO) multilayered films were prepared on Pt/Ti/SiO2/Si substrates by pulsed laser deposition method. It has been demonstrated that the dielectric loss and the leakage current density were significantly reduced with the increase of the SiO2 layer thickness, accompanied with a decrease of the dielectric constant. The CCTO film with a 20 nm SiO2 layer showed a dielectric loss of 0.065 at 100 kHz and the leakage current density of 6×10−7 A/cm2 at 100 kV/cm, which were much lower than those of the single layer CCTO films. The improvement of the electric properties is ascribed to two reasons: one is the improved crystallinity; the other is the reduced free carriers in the multilayered films.