Preparation and characterization of a flexible ferroelectric tunnel junction

摘要

In this work, we propose a flexible ferroelectric tunnel junction (FTJ) with a nanometer-thick single-crystalline BaTiO_3 barrier prepared by exfoliating and transferring epitaxial BaTiO_3 thin films onto flexible poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) conductive electrodes using a water-soluble Sr_3Al_2O_6 sacrificial layer. The transferred freestanding BaTiO_3 films remain single crystalline and exhibit clear ferroelectric hysteresis, no matter being flat or bent. A combined piezoelectric force microscopy and conductive atomic force microscopy measurement reveals that the Pt/BaTiO_3/PEDOT:PSS FTJ shows a clear polarization direction modulated tunneling resistance. By using x-ray photoelectron spectroscopy, the polarization direction-dependent electrostatic potential profile of this flexible FTJ has been reconstructed, consistent with the observed resistance modulation.