Microstructures and electrical properties of CaCu3Ti4O12 thin films on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition

Abstract

We investigated microstructures, compositional distributions, and electrical properties of dielectric CaCu3Ti4O12 (CCTO) thin films deposited on Pt/TiO2/SiO2/Si substrates from 700 to 800 degrees C by pulsed laser deposition. With increasing the deposition temperature from 700 to 750 degrees C, the dielectric constants (epsilon(r)) of CCTO films were greatly enhanced from similar to 300 to similar to 2000 at 10 kHz, respectively. However, the epsilon(r) values of CCTO films were gradually decreased above 750 degrees C, which was surely attributable to the formation of a TiO2-rich dead layer at the interface between CCTO and Pt electrode. Compositional analyses by Auger electron spectroscopy, energy dispersive spectroscopy, and electron energy loss spectroscopy revealed that the TiO2-rich dead layer became thicker because of severe Cu diffusion from CCTO films to Pt electrode. The leakage current behaviors of CCTO films are in good agreement with Poole-Frenkel conduction mechanism, where both the TiO2-rich dead layer and rutile TiO2 nanocrystalline particles are considered to play a role of charge trapping centers.