Ultrahigh stress response and storage properties in a single CdS nanobelt-based flexible device for an erasable nonvolatile stress sensing and memory effect

Abstract

Here, we demonstrate that a single CdS nanobelt with numerous stacking faults, synthesized by a thermal evaporation method, can show a giant stress-response to compressive and tensile strains with an ultrahigh gauge factor of ∼10⁴ and ultrafast millisecond response and recovery speed. After the strains were removed, more importantly, the stress can trigger a high resistance state (HRS), indicative of a nonvolatile stress sensing and memory effect. Moreover, the stress-induced HRS can return to the initial low resistance state (LRS) after a relatively large bias was subsequently applied, indicative of a bias-erasing effect. In nanostructures, numerous stacking faults, serving as trap centres, can capture and store charges. Therefore, the bulk structural defects play a crucial role in superior stress sensing accompanied by an erasable nonvolatile memory effect. Compressive strain can trigger the height of the trap barrier to decrease, whereas tensile strain can trigger it to increase. Therefore, the conductance of the CdS nanobelt regularly increases with an increase in compressive strain. In contrast, it decreases with an increase in tensile strain, showing the strain dependence of conductance. After compressive or tensile strains were removed, in addition, the total number of electrons localized in traps is also reduced, and correspondingly the conductance decreases, showing a nonvolatile stress-writing HRS memory effect. Subsequently, the charges can be injected into traps at a relatively large bias, resulting in the recovery of the LRS, namely an erasable effect. Regarding superior stress-switching accompanied by stress-writing and bias-erasing memory, a multi-defect CdS nanostructure has tremendous potential in nonvolatile stress sensing and memory applications.