  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.
