Enhanced ferroelectric and dielectric behaviors of PZT/BFO heterostructure via compositional development

Abstract

Phase-pure perovskite structure Pb(Zr, Ti)O3 (PZT) thin films are successfully prepared on FTO/glass substrate via magnetron sputtering process, acting as buffer layers for the sol–gel-derived BiFeO3 (BFO) thin film. The existence of compressive strain of PZT buffer layer with various thicknesses was demonstrated through qualitative analysis, which can make the Gibbs-free energy flat and then reduce the ferroelectric domain reversal barrier, thereby influencing the ferroelectric performances. It showed that 100-nm PZT buffer layer is an optimal thickness, and the leakage current density of 100-nm PZT/BFO thin film is significantly decreased by 1–2 orders of magnitudes and the lowest value is obtained. And then BFO/PZT heterostructures in different modes are constructed and the related insulating, ferroelectric and dielectric performance are explored. With 100 nm PZT acting as buffer, enhanced ferroelectricity (at ± 490 kV/cm, Pr = 39.48 µC/cm2, Ec = 125.48 kV/cm) is obtained by modulating the number of interface between BFO and PZT to 7 (marked with Y-7), which is highly related to the reduced leakage current density (at ± 300 kV/cm, 10−5 A/cm2). It can be accounted for existence of compressive stress flattened Gibbs-free energy and increased interfaces number strengthened interfacial polarization. All these indicate that the formation of different heterostructures is promising for obtaining enhanced ferroelectricity.