Microstructures and electrical properties of CaCu 3 Ti 4 O 12 thin films on Pt/TiO 2 /SiO 2 /Si substrates by pulsed laser deposition

We investigated microstructures, compositional distributions, and electrical properties of dielectric CaCu 3 Ti 4 O 12 (CCTO) thin films deposited on Pt/TiO 2 /SiO 2 /Si substrates from 700 to 800 °C by pulsed laser deposition. With increasing the deposition temperature from 700 to 750 °C, the dielectric constants ( e r ) of CCTO films were greatly enhanced from ∼300 to ∼2000 at 10 kHz, respectively. However, the e r values of CCTO films were gradually decreased above 750 °C, which was surely attributable to the formation of a TiO 2 -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 TiO 2 -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 TiO 2 -rich dead layer and rutile TiO 2 nanocrystalline particles are considered to play a role of charge trapping centers.