Strain engineering plays a critical role in ferroelectric memories. In this work, we demonstrate dynamic strain modulation on tunneling electroresistance in a four-unit-cell ultrathin $\mathrm{BaTi}{\mathrm{O}}_3$ metal/ferroelectric/semiconductor tunnel junction by applying mechanical stress to the device. With an extra compressive strain induced by mechanical stress, which is dynamically applied beyond the lattice mismatch between the $\mathrm{BaTi}{\mathrm{O}}_3$ layer and the $\mathrm{Nb}:\mathrm{SrTi}{\mathrm{O}}_3$ substrate, the ON/OFF current ratio increases significantly up to a record high value of ${10}^7$, whereas a mechanical erasing effect can be observed when a tensile stress is applied. This dynamic strain engineering gives rise to an efficient modulation of ON/OFF ratio due to the variation of $\mathrm{BaTi}{\mathrm{O}}_3$ polarization. This result sheds light on the mechanism of electroresistance in the ferroelectric tunnel junctions by providing direct evidence for polarization-induced resistive switching, and also provides another stimulus for memory state operation.

• Received 24 November 2016
• Revised 31 March 2017

DOI:https://doi.org/10.1103/PhysRevB.95.214304