Uniform and ultrathin high-κ gate dielectrics for two-dimensional electronic devices

Abstract

Two-dimensional semiconductors could be used as a channel material in low-power transistors, but the deposition of high-quality, ultrathin high-κ dielectrics on such materials has proved challenging. In particular, atomic layer deposition typically leads to non-uniform nucleation and island formation, creating a porous dielectric layer that suffers from current leakage, particularly when the equivalent oxide thickness is small. Here, we report the atomic layer deposition of high-κ gate dielectrics on two-dimensional semiconductors using a monolayer molecular crystal as a seeding layer. The approach can be used to grow dielectrics with an equivalent oxide thickness of 1 nm on graphene, molybdenum disulfide (MoS2) and tungsten diselenide (WSe2). Compared with dielectrics created using established methods, our dielectrics exhibit a reduced roughness, density of interface states and leakage current, as well as an improved breakdown field. With the technique, we fabricate graphene radio-frequency transistors that operate at 60 GHz, and MoS2 and WSe2 complementary metal–oxide–semiconductor transistors with a supply voltage of 0.8 V and subthreshold swing down to 60 mV dec−1. We also create MoS2 transistors with a channel length of 20 nm, which exhibit an on/off ratio of over 107.

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Fig. 1: Deposition of ultrathin high-κ oxide on 2D materials.
Fig. 2: STEM characterization of gate stacks.
Fig. 3: Dielectric properties on graphene FETs.
Fig. 4: Low-power TMD CMOS.
Fig. 5: Short-channel MoS2 FETs.
Fig. 6: Benchmark of breakdown and leakage characteristics with other technologies.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author on reasonable request.

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Acknowledgements

This work is supported by National Natural Science Foundation of China grants 61734003, 61521001, 61851401, 51861145202, 61861166001, 11874199 and 21872100; National Key Basic Research Programme of China grants 2015CB921600 and 2015CB654901; Natural Science Foundation of Jiangsu Province grants BK20170005; Singapore MOE grant R143-000-A43-114; Programme A for Outstanding Ph.D. candidate of Nanjing University 201801A013; Postgraduate Research & Practice Innovation Programme of Jiangsu Province KYCX18_0045; Strategic Priority Research Programme of Chinese Academy of Sciences XDB 30000000; a Grant-in-Aid for JSPS Research Fellows from the JSPS KAKENHI; the JSPS A3 Foresight Programme and JSPS KAKENHI grants JP19H00755 and 19K21956, Japan; Key Laboratory of Advanced Photonic and Electronic Materials, Collaborative Innovation Centre of Solid-State Lighting and Energy-Saving Electronics, and the Fundamental Research Funds for the Central Universities, China.

Author information

X. Wang conceived and supervised the project. W.L., J. Zhou, Z.Y., N.D., X. Wu., H.Z., D.H., Y.S. and X.D. contributed to sample preparation, characterization, device fabrication, measurements and data analysis. S.C. and P.W. performed TEM and data analysis. J. Zhang and W.C. performed STM and data analysis. N.F. and K.N. performed Dit analysis. T.L. and Z.W. performed CVD sample growth and transfer. Y.W. and T.C. contributed to RF transistor fabrication, measurements and data analysis. X.X. and H.M. performed molecular dynamics simulations. K.Y. and L.P. performed water contact-angle measurement. W.L., Z.Y., P.W. and X. Wang wrote the manuscript with input from other authors. All authors contributed to discussions.

Correspondence to Peng Wang or Xinran Wang.

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Supplementary Information

Supplementary Figs. 1–19 and Tables 1 and 2.

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Li, W., Zhou, J., Cai, S. et al. Uniform and ultrathin high-κ gate dielectrics for two-dimensional electronic devices. Nat Electron 2, 563–571 (2019) doi:10.1038/s41928-019-0334-y

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