Hetero-epitaxial BiFeO3/SrTiO3 nanolaminates with higher piezoresponse performance over stoichiometric BiFeO3 films

Abstract

In this research, BiFeO3 (BFO) films are integrated into BFO/SrTiO3 (STO)/BFO nanolaminates (BSB-NLs) featuring nanometer-scale thickness of BFO and STO layers. By introducing the STO layer in between two BFO layers, the leakage current density is reduced by two orders of magnitude with respect to relatively high leakage currents of current single BFO layers, i.e., from 10−5 A/cm2 to 10−7 A/cm2. The BSB-NL also shows very high piezoelectric response, which is ∼5 times higher than that of the pure BFO with the same thickness. The highly strained state of the BFO layers concurrently with the chemical/crystallographic state of the interfaces between the BFO and STO layers contribute to the very high values of piezoresponse and very low leakage current observed in the BSB-NLs.