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Interaction- and defect-free van der Waals contacts between metals and two-dimensional semiconductors

Nature Electronics volume 5, pages 241–247 (2022)Cite this article

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Abstract

High Schottky barrier heights at metal–semiconductor junctions due to Fermi-level pinning can degrade the performance of electronic devices and increase their energy consumption. Van der Waals contacts between metals and two-dimensional semiconductors without Fermi-level pinning are theoretically possible, but have not been achieved due to the presence of interactions such as interface defects and orbital overlap. Here we show that interaction- and defect-free van der Waals contacts can be formed between a range of metals and two-dimensional semiconductors via a metal deposition process that uses a selenium buffer layer. Our contacts obey the Schottky–Mott rule and have a Fermi-level pinning of –0.91. A comparison between the van der Waals contacts and typical direct metal contacts reveals differences in interface gap distances, band bending and electrical characteristics. Using gold van der Waals contacts, we fabricate p-type tungsten diselenide field-effect transistors that exhibit stable operation with on/off ratio of 106, mobility of 155 cm2 (V s)–1, contact resistance of 1.25 kΩ μm and Schottky barrier height of 60 meV.

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Fig. 1: WSe2 with vdW and direct Au contact.
Fig. 2: FET properties of WSe2 with vdW and direct Au contact.
Fig. 3: DFT results for WSe2 with vdW and direct Au contact.
Fig. 4: Properties of FETs made of various TMDs with vdW and direct metal contact.
Fig. 5: SBH between WSe2 and various vdW and direct metal contacts, and output curves of vdW metal contacts.

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

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Acknowledgements

This work was partially supported by an Industry–Academy joint research programme between Samsung Electronics and Yonsei University. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (grant no. 2017R1A5A1014862; SRC programme, vdWMRC center). This work was supported by the NRF grant funded by the Government of Korea (MSIP) (no. 2021M3H4A1A03052566).

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Authors and Affiliations

  1. Department of Physics, Yonsei University, Seoul, Republic of Korea

    Gihyeon Kwon, Yoon-Ho Choi, Hyeon-Sik Kim, Jeahun Jeong, Min Baik, Hoedon Kwon & Mann-Ho Cho

  2. Yield Enhancement team, Foundry, Samsung Electronics, Hwaseong-si, Republic of Korea

    Yoon-Ho Choi

  3. Analytical Engineering Group, Samsung Advanced Institute of Technology, Samsung Electronics, Suwon, Republic of Korea

    Hyangsook Lee, Jaemin Ahn & Eunha Lee

  4. Division of Physics and Semiconductor Science, Dongguk University, Seoul, Republic of Korea

    Kwangsik Jeong

  5. Department of System Semiconductor Engineering, Yonsei University, Seoul, Republic of Korea

    Mann-Ho Cho

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  1. Gihyeon Kwon
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Contributions

G.K. conceived the research and designed the experiments with the help of M.-H.C. G.K., Y.-H.C., H. Kim and J.J. contributed to the device fabrication and setting the equipment. G.K., Y.-H.C., H. Kim, J.J., M.B. and H. Kwon performed the experiments and data analysis. K.J. contributed to the DFT calculations. H.L., J.A. and E.L. made a significant contribution to the STEM measurement and analysis. The manuscript was written by G.K. and revised by M.-H.C. All the experiments and analyses were supervised by M.-H.C.

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Correspondence to Eunha Lee or Mann-Ho Cho.

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Kwon, G., Choi, YH., Lee, H. et al. Interaction- and defect-free van der Waals contacts between metals and two-dimensional semiconductors. Nat Electron 5, 241–247 (2022). https://doi.org/10.1038/s41928-022-00746-6

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