Low-resistance metal contacts to encapsulated semiconductor monolayers with long transfer length – Nature.com

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Nature Electronics volume 5, pages 579–585 (2022)Cite this article
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Two-dimensional semiconductors such as transition metal dichalcogenides are of potential use in electronic and optoelectronic devices due to their high mobility, direct optical bandgap and mechanical flexibility. These semiconductors are often encapsulated with hexagonal boron nitride to minimize extrinsic disorder and improve performance, but it is challenging to make high-quality contacts to encapsulated high-purity monolayers. Here we show that metal contacts embedded within hexagonal boron nitride can be transferred onto clean transition metal dichalcogenide monolayers, in an approach that reduces doping, strain and interfacial roughness compared with evaporated metal contacts. Contacts to encapsulated ultraclean tungsten diselenide monolayers created using this technique exhibit a room-temperature contact resistance of around 5 kΩ μm, and provide transistors with zero hysteresis and room-temperature mobility of 655 cm² V⁻¹ s⁻¹. The contacts also exhibit a transfer length of 1 μm, which is several orders of magnitude larger than the channel thickness.
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The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.
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This work was primarily supported by the NSF MRSEC program at Columbia through the Center for Precision-Assembled Quantum Materials (DMR-2011738), in collaboration with the National Research Foundation of Korea through the Global Research Laboratory Program (2016K1A1A2912707). Control experiments (Z.W.) were supported by the Department of Energy (DE-SC0016703). Synthesis of boron nitride (K.W. and T.T.) was supported by the Elemental Strategy Initiative conducted by the MEXT, Japan (grant no. JPMXP0112101001), and JSPS KAKENHI (grant nos. JP19H05790 and JP20H00354).
Department of Mechanical Engineering, Columbia University, New York, NY, USA
Yang Liu, Song Liu, Zhiying Wang, Baichang Li & James Hone
Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
Kenji Watanabe
International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
Takashi Taniguchi
SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, Korea
Won Jong Yoo
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Y.L. conceived, led and was involved in all aspects of the project and performed all the design, fabrication, measurement, simulation and data analysis. S.L. grew the WSe₂ crystals and performed the scanning tunnelling microscopy characterizations of the bulk WSe₂ crystals. Z.W. performed the control experiments with evaporated contacts. K.W. and T.T. grew the hBN crystals. W.J.Y. and J.H. advised on the project. Y.L. and J.H. discussed the results and co-wrote the manuscript with input from all the authors.
Correspondence to Yang Liu or James Hone.
The authors declare no competing interests.
Nature Electronics thanks Takamasa Kawanago, Seongjun Park and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Liu, Y., Liu, S., Wang, Z. et al. Low-resistance metal contacts to encapsulated semiconductor monolayers with long transfer length. Nat Electron 5, 579–585 (2022). https://doi.org/10.1038/s41928-022-00808-9
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Received: 01 October 2021
Accepted: 08 July 2022
Published: 01 September 2022
Issue Date: September 2022
DOI: https://doi.org/10.1038/s41928-022-00808-9
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