Microstructure and dielectric properties of pulsed-laser-deposited CaCu3Ti4O12 thin films on LaNiO3 buffered Pt/Ti/SiO2/Si substrates

Abstract

CaCu3Ti4O12 (CCTO) thin films have been prepared by a pulsed-laser-deposition method on LaNiO3 buffered Pt/Ti/SiO2/Si substrates, and their microstructure and dielectric properties have been compared with those of the films deposited directly on Pt/Ti/SiO2/Si substrates. The crystalline structure and the surface morphology of the CCTO thin films were markedly affected by the bottom electrodes. Both the films show temperature-independent dielectric properties in a wide temperature range, which is similar to those properties obtained in single-crystal or epitaxial thin films, while the room-temperature dielectric constant of the 350-nm-thick CCTO films on LaNiO3/Pt/Ti/SiO2/Si substrates at 100 kHz was found to be 2300, which was increased significantly compared with that obtained in the films on Pt/Ti/SiO2/Si substrates. Using the impedance spectroscopy technique, it has been suggested that the high dielectric constant response of the CCTO thin films originates from the grain boundary layer mechanism as found in internal barrier layer capacitors.