Improved Dielectric Properties of CaCu3Ti4O12 films with a CaTiO3 Inter layer on Pt/TiO2/SiO2/Si Substrates Prepared by Pulsed Laser Deposition

We report the greatly improved dielectric properties of CaCu3Ti4O12 (CCTO) films with a 60 nm-thick CaTiO3 (CTO) interlayer on Pt/TiO2/SiO2/Si substrates. Both CCTO films and CTO interlayers were prepared by pulsed laser deposition (PLD). With increasing the thickness of CCTO from 200 nm to 1.3 mu m, the dielectric constants (epsilon(r)) at 10 kHz in both CCTO single-layered and CCTO/CTO double-layered films increased from 260 to 6000 and from 630 to 3700, respectively. Compared with CCTO single-layered films, CCTO/CTO double-layered films irrespective of CCTO film thickness exhibited a remarkable decrease in their dielectric losses (tan delta) (<0.1 at the frequency region of 1 - 100 kHz) and highly reduced leakage current density at room temperature. The reduced leakage currents in CCTO/CTO double-layered films are attributable to relatively higher trap ionization energies in the Poole-Frenkel conduction model.