Effect of superlattice-like multilayer structure on ferroelectric BiFe_0.97Cr_0.03O₃/BiFe_1-xMn_xO₃ composite thin films

Pure bismuth ferrate thin films often have a high leakage conductance and low polarization, which has greatly limited the application of bismuth ferrate thin films in electron devices. Here, the low mismatch interface of the BiFe_0.97Cr_0.03O₃/BiFe_1-xMn_xO₃ (x = 0.01–0.09) superlattice-like multilayer composite thin films are constructed, and the high leakage current and false polarization phenomenon of BiFe_0.97Cr_0.03O₃/BiFe_1-xMn_xO₃ superlattice-like multilayer composite thin films are regulated by the interface composite. The BFC_0.03O/BFM_0.09O sample had the highest rectangles (1.18) with larger residual polarization value (82 μC/cm²), lower coercive field (265.05 kV/cm) and the largest polarization turnover current (0.56 mA). The BFC_0.03O/BFM_0.09O sample mainly possessed 60° domain structures by piezoresponse force microscopy (PFM). In addition, the relationship between the false polarization and the built-in electric field is analyzed, and the contribution of the built-in electric field caused by defects (E_bi) and the built-in electric field caused by strain gradient (E_flexo) to the total built-in electric field is further studied.