Mechanical force-driven multi-state memory in WO3–δ thin films†
Abstract
Multi-state resistive switching memory has attracted attention in the development of information technology owing to its high storage density and rapid switching. However, the degradation of their resistive properties caused by charge accumulation after multiple electric-field switching severely restricts the practical application of resistive switching devices. Herein, mechanical force rather than electric field is used to prevent charge accumulation in WO3–δ thin films, which is a paradigm material possessing excellent resistive switching properties and the capability to withstand significant structural distortion. The mechanical force applied through the probe tip creates an enormous inhomogeneous strain that penetrates the entire WO3–δ thin film, resulting in lattice distortion and a flexoelectric field inside the WO3–δ thin film, weakening the built-in electric field formed at the metal–semiconductor interface and the Schottky barrier. Eventually, excellent resistive switching is obtained with a high ON/OFF ratio (maximum >1000) and faster writing speeds. Modulating the multi-state through mechanical force can not only obtain high-performance resistive switching, but also provide a novel method to achieve multi-level memories through multi-field coupling.