Dielectric properties of CaCu3Ti4O12 thin films

High dielectric CaCu₃Ti₄O₁₂ (CCTO) thin films were successfully grown on LaAlO₃(100) (LAO) crystalline substrates and on SrRuO₃(SRO) conductive films on LAO substrates by the pulsed laser deposition (PLD) method. Microstructure and dielectric properties of (001) oriented (CCTO) epitaxial thin films were evaluated, and compared to those of CCTO polycrystalline bulk samples by x-ray diffraction, DC conductivity and dielectric measurements. The gigantic dielectric constant of greater than 20,000 in polycrystalline CCTO can be accounted for by the internal barrier layer capacitance (IBLC) model. However, this model fails to explain the large dielectric constant behavior for epitaxial CCTO/SRO/LAO thin films which also show high DC conductivity. XPS analysis indicated that oxygen vacancies could be a possible factor responsible for the low resistivity of thin film.