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Transferred van der Waals metal electrodes for sub-1-nm MoS2 vertical transistors

Abstract

Vertical transistors—in which the channel length is determined by the thickness of the semiconductor—are of interest in the development of next-generation electronic devices. However, short-channel vertical devices are difficult to fabricate, because the high-energy metallization process typically results in damage to the contact region. Here we show that molybdenum disulfide (MoS2) vertical transistors with channel lengths down to one atomic layer can be created using a low-energy van der Waals metal integration technique. The approach uses prefabricated metal electrodes that are mechanically laminated and transferred on top of MoS2/graphene vertical heterostructures, leading to vertical field-effect transistors with on–off ratios of 26 and 103 for channel lengths of 0.65 nm and 3.60 nm, respectively. Using scanning tunnelling microscopy and low-temperature electrical measurements, we show that the improved electrical performance is the result of a high-quality metal–semiconductor interface, with minimized direct tunnelling current and Fermi-level pinning effect. The approach can also be extended to other layered materials (tungsten diselenide and tungsten disulfide), resulting in sub-3-nm p-type and n-type vertical transistors.

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Fig. 1: Device fabrication processes of MoS2 VFET and characterization of Au–2D interface.
Fig. 2: Transfer characteristics of MoS2 VFETs with evaporated and vdW metal electrodes.
Fig. 3: Temperature-dependent charge transport in the MoS2 VFETs.
Fig. 4: WSe2 and WS2 VFETs with evaporated and transferred metal electrodes.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

Y.L. acknowledges financial support from the National Natural Science Foundation of China (grant nos. 51991340, 51991341, 51802090 and 61874041) and from the Hunan Science Fund for Excellent Young Scholars (grant no. 812019037). L. Liao acknowledges financial support from the National Key Research and Development Program of China (grant no. 2018YFA0703704). A.P. acknowledges financial support from the National Natural Science Foundation of China (grant nos. 62090035 and U19A2090).

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Contributions

Y.L. conceived and supervised the research. Y.L. and L. Liu designed the experiments. L. Liu performed the device fabrication, low-temperature measurement and data analysis. L.K., Q.L., L.R., Q.T., X.Y., J.L., Z. Li, W.L., W.S., G.L. and L. Liao contributed to device fabrication. L.K. and Q.T. contributed to the device electrical measurements. Y.C., L.K. and Z. Lu contributed to discussions and data analysis. Z. Li and W.S. contributed to the atomic force microscopy measurement. C.H., B.Z., X.Y., S.L., X.D. and A.P. contributed to the STM measurement. Y.L. and L. Liu co-wrote the manuscript. All the authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Yuan Liu.

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The authors declare no competing interests.

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Peer review information Nature Electronics thanks PingAn Hu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–16.

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Liu, L., Kong, L., Li, Q. et al. Transferred van der Waals metal electrodes for sub-1-nm MoS2 vertical transistors. Nat Electron 4, 342–347 (2021). https://doi.org/10.1038/s41928-021-00566-0

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