Stripe domains in epitaxial BiFeO3 thin films on (100) SrTiO3 substrates

Abstract

Highly crystallized ferroelectric BiFeO3 thin films were deposited on various miscut (100) SrTiO3 substrates. The domain structure of the films varies with substrate miscut angles and atomic-layer termination at the surface. The BiFeO3 thin films grown on 4° miscut substrates exhibit 71° periodic stripe domains consisting of two downward polarization variants. In contrast, four downward variants coexist in the films deposited on 0.2° miscut substrates, regardless of atomic-layer termination at the surface of the substrate. The introduction of an additional SrTiO3 repair layer on the same substrate results in a step-flow growth mode of the film. It is believed that the improved mobility of the BiFeO3 atomic species during the film growth leads to the appearance of preferred ferroelectric variants at the step edges. These preferred variants eventually form stripe domains. Our results reveal that both the miscut angle and the step-flow growth promote the formation of the two variant striped domains in BiFeO3 films deposited on decorated isotropic SrTiO3 substrates.