Effects of post-anneal conditions on the dielectric properties of CaCu3Ti4O12 thin films prepared on Pt/Ti/SiO2/Si substrates

High-dielectric-constant CaCu3Ti4O12 (CCTO) thin films were prepared on Pt/Ti/SiO2/Si(100) substrates by pulsed-laser deposition. The 480 nm thick polycrystalline films have preferred orientation and show obvious crystallization on the surface. The temperature-dependence of dielectric constant and loss of the Pt/CCTO/Pt capacitors is comparable with that of epitaxial CCTO films grown on oxides substrates. We found that the dielectric properties are very sensitive to the post-annealing atmosphere and temperature. Post-annealing in nitrogen atmosphere produces larger low-frequency dielectric relaxation as the annealing temperature increases, while annealing in oxygen atmosphere at high temperature suppresses the relaxation but lowers the dielectric constant. Such results are attributed to the presence of insulating grain boundary barrier layers.