Enhanced Ferroelectric and Piezoelectric Properties in Graphene-Electroded Pb(Zr,Ti)O₃ Thin Films

While using ferroelectric polarization to tune the functional properties of 2D materials has been extensively studied recently, the effects of 2D materials on the ferroelectricity and piezoelectricity of ferroelectrics are much less explored. In this work, we report markedly enhanced ferroelectric and piezoelectric properties of graphene/Pb(Zr0.52Ti0.48)O3/SrRuO3 (GR/PZT/SRO) capacitors. Compared with conventional metal-electroded ferroelectric capacitors, the GR/PZT/SRO capacitors exhibit more abrupt polarization switching, larger switchable polarization, lower leakage current, and smaller coercive voltage. Moreover, with graphene electrodes, the ferroelectric properties of PZT capacitors are much more stable against aging. The enhanced ferroelectric behaviors in GR/PZT/SRO capacitors can be attributed to an improved interface with fewer defects and inhibited growth of defective interfacial layer resulting from the graphene protection. Because of the atomic thickness and extraordinary mechanical flexibility of graphene, the piezoelectric response in PZT with graphene electrode is about four times larger than the one with an Au electrode. Our findings on the enhanced ferroelectric and piezoelectric properties of PZT with 2D electrodes advance the understanding of the 2D/PZT interface and provide solutions for developing high-performance ferroelectrics devices.