Non-volatile resistive switching, also known as memristor1 effect, where an electric field switches the resistance states of a two-terminal device, has emerged as an important concept in the development of high-density information storage, computing and reconfigurable systems2,3,4,5,6,7,8,9. The past decade has witnessed substantial advances in non-volatile resistive switching materials such as metal oxides and solid electrolytes. It was long believed that leakage currents would prevent the observation of this phenomenon for nanometre-thin insulating layers. However, the recent discovery of non-volatile resistive switching in two-dimensional monolayers of transition metal dichalcogenide10,11 and hexagonal boron nitride12 sandwich structures (also known as atomristors) has refuted this belief and added a new materials dimension owing to the benefits of size scaling10,13. Here we elucidate the origin of the switching mechanism in atomic sheets using monolayer MoS2 as a model system. Atomistic imaging and spectroscopy reveal that metal substitution into a sulfur vacancy results in a non-volatile change in the resistance, which is corroborated by computational studies of defect structures and electronic states. These findings provide an atomistic understanding of non-volatile switching and open a new direction in precision defect engineering, down to a single defect, towards achieving the smallest memristor for applications in ultra-dense memory, neuromorphic computing and radio-frequency communication systems2,3,11.
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The authors declare that the main data supporting the findings of this study are available within the Letter and its Supplementary Information. Extra data are available from the corresponding author upon reasonable request. Source data are provided with this paper.
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This work was supported in part by the Presidential Early Career Award for Scientists and Engineers (PECASE) through the Army Research Office (W911NF-16-1-0277), and a National Science Foundation grant (ECCS-1809017). S.M.H. acknowledges support from a US S&T Cooperation Program. The facilities of the Center for Dynamics and Control of Materials: an NSF Materials Research Science and Engineering Center (MRSEC) was used for materials characterization. A portion of this research, including STM, transport measurements and STM simulations, was conducted at the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, which is a US Department of Energy User Facility. We thank W. R. Hendren and R. M. Bowman for their help with the metal film deposition.
The authors declare no competing interests.
Peer review information Nature Nanotechnology thanks Hyeon-Jin Shin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Hus, S.M., Ge, R., Chen, PA. et al. Observation of single-defect memristor in an MoS2 atomic sheet. Nat. Nanotechnol. 16, 58–62 (2021). https://doi.org/10.1038/s41565-020-00789-w