Effect of polarization on tunnelling electroresistance in ferroelectric tunnel junctions

Abstract

High-quality epitaxial BiFeO3 (BFO) films were grown on (001)-, (110)-, and (111)-oriented Nb:SrTiO3 (NSTO) substrates by pulsed laser deposition. The types of domain structures can be modulated by BFO ferroelectric films with different crystalline orientations. The ON/OFF ratios are 6E3, 3E4 and 2E5 obtained in (001)-, (110)-, and (111)-oriented Au/BFO/NSTO ferroelectric tunnel junctions (FTJs), respectively. The analysis of the I-V curves of tunneling current and average BFO ferroelectric barrier height prove that the polarization intensity of the BFO films modulate both ferroelectric barrier and Schottky barrier profile, which further influences the electronic tunneling probability in the BFO FTJs. This work will be useful for further study on achieving giant ON/OFF ratio and developing insights on the barrier profile and transport mechanism of MFS-type FTJs.