Ferroelectric-induced resistive switching in ultrathin (Ba,Sr)TiO3 tunnel junctions due to strain modulation

Abstract

Through strain modulation to the (Ba-0.8,Sr-0.2)TiO3 (BST) tunnel junction, giant resistive switching was achieved in a Pt/BST/Nb:SrTiO3 (Nb:STO) heterostructure, and the role of ferroelectricity in the resistive switching was studied. When an external compressive strain was added to this heterostructure with a ten-unit-cell-thick BST tunnel layer, the resistive switching mechanism was demonstrated to change from thermionic emission to direct tunneling accompanied by the ferroelectricity enhancement to the BST layer. This reveals the role of strain and ferroelectricity in resistive switching which leads to three orders increase in the ON/OFF current ratio for the BST tunnel layer. These encouraging results not only show the potential to enhance ferroelectricity of BST thin film by strain engineering, but also the crucial role of strain engineering in BST tunnel layer-based memory device applications. Published by AIP Publishing.