Abstract
Heterostructures made using two-dimensional semiconducting transition metal dichalcogenides could be used to build next-generation electronic devices. However, their performance is limited by low-quality metal–semiconductor contacts, and it remains challenging to create contacts with variable work functions using metals or metallic transition metal dichalcogenides. Here we show that a one-step chemical vapour deposition method can be used to fabricate nanoplates of a two-dimensional metallic alloy VS2xSe2(1–x) (where 0 ≤ x ≤ 1), which has a continuously tunable band alignment. The work function of the alloy can vary from 4.79 ± 0.01 eV (VSe2, x = 0) to 4.64 ± 0.01 eV (VS2, x = 1.00). The van der Waals heterostructures of VS2xSe2(1–x) and p-type tungsten diselenide (WSe2) exhibit increased contact potential difference as x varies from 0 to 1, with transistors made using VSe2/WSe2 contacts showing a lower potential difference and better device performance than transistors with VSSe/WSe2 contacts, and in both cases, achieve better performance than devices with evaporated metal contacts. The contact potential difference in heterostructures of the alloy and n-type molybdenum disulfide can be turned from −71.5 mV (VSe2) to 0 mV (VSSe) to 59.3 mV (VS2)—that is, from Schottky to ohmic contacts—with the lowest-work-function (VS2) transistors showing the best performance.
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Acknowledgements
We acknowledge support from the National Key R&D Program of the Ministry of Science and Technology of China (grant no. 2022YFA1203801 to X.D.); the National Natural Science Foundation of China (grant nos. 51991340, 51991343, 52221001 and 52102168 to X.D. and J.L.); the Hunan Key R&D Program Project (grant no. 2022GK2005 to X.D.); the Natural Science Foundation of Hunan Province (grant no. 2023JJ20009 to J.L.); the Ningbo Natural Science Foundation (grant no. 2023J023 to X.Y.); and the Natural Science Foundation of Chongqing, China (grant no. cstc2021jcyj-msxmX0321 to J.L.). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript.
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X.D. and J. Li conceived the research and designed the experiments. X.L. developed a method to grow VS2xSe2(1–x) alloy nanoplates and their heterostructures and fabricated and measured all the devices. H.L. performed the KPFM study. J.Z. performed the DFT calculations. F.D., R.S., W.H., J. Liang and W.L. participated in the material growth. Zucheng Zhang, J.L., X.Y. and R.W. participated in the device fabrication. Y.L., B.L., B.Z., J. Liu, Z.W. and Zhengwei Zhang contributed to the discussion and data analysis. X.L., J. Li and X.D. co-wrote the manuscript with input from all the authors. All authors discussed the results and commented on the manuscript.
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Li, X., Long, H., Zhong, J. et al. Two-dimensional metallic alloy contacts with composition-tunable work functions. Nat Electron 6, 842–851 (2023). https://doi.org/10.1038/s41928-023-01050-7
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DOI: https://doi.org/10.1038/s41928-023-01050-7
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