Effects of post-anneal conditions on the dielectric properties of CaCu3Ti4O12 thin films prepared on Pt/Ti/SiO2/Si substrates

TL;DR

This study investigates how different post-annealing atmospheres and temperatures affect the dielectric properties of CaCu3Ti4O12 thin films, revealing that annealing conditions significantly influence dielectric relaxation and constant due to grain boundary effects.

Contribution

It provides new insights into the impact of post-annealing atmospheres on the dielectric behavior of CCTO thin films, highlighting the role of grain boundary barriers.

Findings

Nitrogen annealing increases low-frequency dielectric relaxation with higher temperatures.

Oxygen annealing suppresses dielectric relaxation but reduces dielectric constant.

Dielectric properties are highly sensitive to annealing atmosphere and temperature.

Abstract

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.