Ultralow contact resistance between semimetal and monolayer semiconductors

Pin-Chun Shen, Cong Su, Yuxuan Lin, Ang-Sheng Chou, Chao-Ching Cheng, Ji-Hoon Park, Ming-Hui Chiu, Ang-Yu Lu, Hao-Ling Tang, Mohammad Mahdi Tavakoli, Gregory Pitner, Xiang Ji, Zhengyang Cai, Nannan Mao, Jiangtao Wang, Vincent Tung, Ju Li, Jeffrey Bokor, Alex Zettl, Chih-I WuTomás Palacios, Lain-Jong Li, Jing Kong

Research output: Contribution to journalArticlepeer-review

610 Scopus citations


Advanced beyond-silicon electronic technology requires both channel materials and also ultralow-resistance contacts to be discovered1,2. Atomically thin two-dimensional semiconductors have great potential for realizing high-performance electronic devices1,3. However, owing to metal-induced gap states (MIGS)4–7, energy barriers at the metal–semiconductor interface—which fundamentally lead to high contact resistance and poor current-delivery capability—have constrained the improvement of two-dimensional semiconductor transistors so far2,8,9. Here we report ohmic contact between semimetallic bismuth and semiconducting monolayer transition metal dichalcogenides (TMDs) where the MIGS are sufficiently suppressed and degenerate states in the TMD are spontaneously formed in contact with bismuth. Through this approach, we achieve zero Schottky barrier height, a contact resistance of 123 ohm micrometres and an on-state current density of 1,135 microamps per micrometre on monolayer MoS2; these two values are, to the best of our knowledge, the lowest and highest yet recorded, respectively. We also demonstrate that excellent ohmic contacts can be formed on various monolayer semiconductors, including MoS2, WS2 and WSe2. Our reported contact resistances are a substantial improvement for two-dimensional semiconductors, and approach the quantum limit. This technology unveils the potential of high-performance monolayer transistors that are on par with state-of-the-art three-dimensional semiconductors, enabling further device downscaling and extending Moore’s law.
Original languageEnglish (US)
Pages (from-to)211-217
Number of pages7
Issue number7858
StatePublished - May 12 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-06-11
Acknowledged KAUST grant number(s): OSR-2018-CARF/CCF-3079
Acknowledgements: P.-C.S., J.B. and J.K. acknowledge financial support from the Center for Energy Efficient Electronics Science (NSF award no. 0939514), which provided funding for development of high-performance monolayer TMD transistors. P.-C.S., Y.L., J.-H.P., A.-Y.L., T.P. and J.K. acknowledge the US Army Research Office through the Institute for Soldier Nanotechnologies at MIT, under cooperative agreement no. W911NF-18-2-0048. C.S., J.-H.P., J.W. and J.K. acknowledge the support from the US Army Research Office (ARO) under grant no. W911NF-18-1-0431. C.S. is currently supported by the Kavli Energy NanoScience Institute/Heising–Simons Fellowship, Berkeley, California, USA. C.S. and A.Z. are supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, of the US Department of Energy under contract no. DE-AC02-05-CH11231, within the sp2-Bonded Materials Program (KC2207), which provided for TEM characterizations. C.S. and A.Z. are further supported by the National Science Foundation under grant no. DMR-1807233, which provided funding for development of TEM image-processing methods. J.L. acknowledges support by the Office of Naval Research MURI through grant no. N00014-17-1-2661. Y.L. and J.B. acknowledge support by the Office of Naval Research MURI programme N00014-16-1-2921, and the NSF award RAISE TAQS under grant no. DMR-1839098. Y.L. and N.M. acknowledge support by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under award DE-SC0020042. A.-S.C. and C.-I.W. acknowledge support from the Ministry of Science and Technology of Taiwan (MOST 108-2622-8-002-016). J.W. and J.K. acknowledge support from the joint development project (JDP) from TSMC. V.T. and M.-H.C. are indebted to the support from the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no: OSR-2018-CARF/CCF-3079. H.-L.T. acknowledges partial support from the Ministry of Science and Technology of Taiwan (MOST-108-2917-I-564-036). We acknowledge H.-S.P. Wong for guidance. We thank Y. Guo, E. Shi and H. Wang for technical assistance with materials characterizations, and Y.-T. Shao for discussions on SAED pattern simulation.

ASJC Scopus subject areas

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