Preferential orientation and relaxation behaviors of CaCu3Ti4O12 thin films in a low frequency range

Abstract

Abstract CaCu3Ti4O12 (CCTO) thin films were deposited on Pt/Ti/SiO2/Si substrate at 500 °C by radio frequency magnetron sputtering. The influences of annealing atmosphere on structures and dielectric behaviors of CCTO films were investigated. Pure cubic phase was confirmed for all samples. Especially preferential (422) orientation was dominant of annealed thin films than the as-deposited one. Meanwhile, dielectric relaxation behaviors were different from the as-deposited films and the annealed ones: the relaxation at middle frequency of the as-deposited films originated from the secondary ionization of oxygen vacancy disappeared after annealing. Additionally, oxygen atmosphere annealing caused a high relative dielectric constant up to ∼104 at low frequency of 1 Hz, that was two orders of magnitude higher than the as-deposited one. It should be ascribed to well crystallization after heating in oxygen. On the other hand, the real part of the dielectric permittivity of the annealed films were much more irrelevant with frequency and temperature than the as-deposited one, which were potential for mass and stable storage in the microelectronics industry.