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.
This is a preview of subscription content
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the plots within this paper and other findings of this study are available from the corresponding author on reasonable request.
Theis, T. N. & Wong, H. S. P. The end of Moore’s law: a new beginning for information technology. Comput. Sci. Eng. 19, 41–50 (2017).
Natarajan, S. et al. A 14nm logic technology featuring 2nd-generation FinFET interconnects, self-aligned double patterning and a 0.0588 µm2 SRAM cell size. In Proc. 2014 IEEE International Electron Devices Meeting 3.7.1–3.7.3 (IEEE, 2014).
Robertson, J. High dielectric constant oxides. Eur. Phys. J. Appl. Phys. 28, 265–291 (2004).
Chhowalla, M., Jena, D. & Zhang, H. Two-dimensional semiconductors for transistors. Nat. Rev. Mater. 11, 16052 (2016).
Fiori, G. et al. Electronics based on two-dimensional materials. Nat. Nanotechnol. 9, 768–779 (2014).
Desai, S. B. et al. MoS2 transistors with 1-nanometer gate lengths. Science 354, 99–102 (2016).
Radisavljevic, B., Radenovic, A., Brivio, J., Giacometti, V. & Kis, A. Single-layer MoS2 transistors. Nat. Nanotechnol. 6, 147–150 (2011).
Kim, H. G. & Lee, H. B. R. Atomic layer deposition on 2D materials. Chem. Mater. 29, 3809–3826 (2017).
Zhu, Y. et al. Monolayer molybdenum disulfide transistors with single-atom-thick gates. Nano Lett. 18, 3807–3813 (2018).
Wang, X., Tabakman, S. M. & Dai, H. Atomic layer deposition of metal oxides on pristine and functionalized graphene. J. Am. Chem. Soc. 130, 8152–8153 (2008).
Park, J. H. et al. Atomic layer deposition of Al2O3 on WSe2 functionalized by titanyl phthalocyanine. ACS Nano 10, 6888–6896 (2016).
Alaboson, J. M. et al. Seeding atomic layer deposition of high-κ dielectrics on epitaxial graphene with organic self-assembled monolayers. ACS Nano 5, 5223–5232 (2011).
Johns, J. E., Karmel, H. J., Alaboson, J. M. & Hersam, M. C. Probing the structure and chemistry of perylenetetracarboxylic dianhydride on graphene before and after atomic layer deposition of alumina. J. Phys. Chem. Lett. 3, 1974–1979 (2012).
Britnell, L. et al. Electron tunneling through ultrathin boron nitride crystalline barriers. Nano Lett. 12, 1707–1710 (2012).
Wang, J. et al. Integration of high-k oxide on MoS2 by using ozone pretreatment for high-performance MoS2 top-gated transistor with thickness-dependent carrier scattering investigation. Small 11, 5932–5938 (2015).
Wang, X. et al. Improved integration of ultra-thin high-k dielectrics in few-layer MoS2 FET by remote forming gas plasma pretreatment. Appl. Phys. Lett. 110, 53110 (2017).
Xiao, M., Qiu, C., Zhang, Z. & Peng, L. Atomic-layer-deposition growth of an ultrathin HfO2 film on graphene. ACS Appl. Mater. Interfaces 9, 34050–34056 (2017).
Liu, Y. et al. Approaching the Schottky–Mott limit in van der Waals metal–semiconductor junctions. Nature 557, 696–700 (2018).
Sangwan, V. K. et al. Quantitatively enhanced reliability and uniformity of high-κ dielectrics on graphene enabled by self-assembled seeding layers. Nano Lett. 13, 1162–1167 (2013).
Dean, C. R. et al. Boron nitride substrates for high-quality graphene electronics. Nat. Nanotechnol. 5, 722–726 (2010).
Yang, L. et al. 10 nm nominal channel length MoS2 FETs with EOT 2.5 nm and 0.52 mA/µm drain current. In Proc. 73rd Annual Device Research Conference 237–238 (IEEE, 2015).
Liao, L. et al. Top-gated graphene nanoribbon transistors with ultrathin high-κ dielectrics. Nano Lett. 10, 1917–1921 (2010).
Liao, L. et al. Sub-100 nm channel length graphene transistors. Nano Lett. 10, 3952–3956 (2010).
Cheng, R. et al. Few-layer molybdenum disulfide transistors and circuits for high-speed flexible electronics. Nat. Commun. 5, 5143 (2014).
Wu, B. et al. Precise, self-limited epitaxy of ultrathin organic semiconductors and heterojunctions tailored by van der Waals interactions. Nano Lett. 16, 3754–3759 (2016).
Wang, Q. H. & Hersam, M. C. Room-temperature molecular-resolution characterization of self-assembled organic monolayers on epitaxial graphene. Nat. Chem. 1, 206–211 (2009).
Zhao, Y., Wu, Q., Chen, Q. & Wang, J. Molecular self-assembly on two-dimensional atomic crystals: insights from molecular dynamics simulations. J. Phys. Chem. Lett. 6, 4518–4524 (2015).
Martin, J. M., Vacher, B., Ponsonnet, L. & Dupuis, V. Chemical bond mapping of carbon by image-spectrum EELS in the second derivative mode. Ultramicroscopy 65, 229–238 (1996).
Wang, X., Xu, J. B., Wang, C., Du, J. & Xie, W. High-performance graphene devices on SiO2/Si substrate modified by highly ordered self-assembled monolayers. Adv. Mater. 23, 2464–2468 (2011).
Zou, X. et al. Interface engineering for high-performance top-gated MoS2 field-effect transistors. Adv. Mater. 26, 6255–6261 (2014).
Wang, B. et al. High-κ gate dielectrics for emerging flexible and stretchable electronics. Chem. Rev. 118, 5690–5754 (2018).
Cheng, R. et al. High-frequency self-aligned graphene transistors with transferred gate stacks. Proc. Natl Acad. Sci. USA 109, 11588–11592 (2012).
Wu, Y. et al. High-frequency, scaled graphene transistors on diamond-like carbon. Nature 472, 74–78 (2011).
Yu, Z. et al. Realization of room-temperature phonon-limited carrier transport in monolayer MoS2 by dielectric and carrier screening. Adv. Mater. 28, 547–552 (2016).
International Technology Roadmap for Semiconductors www.itrs.net/2013-itrs.html (Semiconductor Industry Association, 2013).
Pu, J. et al. Highly flexible and high-performance complementary inverters of large-area transition metal dichalcogenide monolayers. Adv. Mater. 28, 4111–4119 (2016).
Fang, N. & Nagashio, K. Band tail interface states and quantum capacitance in a monolayer molybdenum disulfide field-effect-transistor. J. Phys. D 51, 65110 (2018).
Liu, H. & Ye, P. D. MoS2 dual-gate MOSFET with atomic-layer-deposited Al2O3 as top-gate dielectric. IEEE Electron Device Lett. 33, 546–548 (2012).
Salvatore, G. A. et al. Fabrication and transfer of flexible few-layers MoS2 thin film transistors to any arbitrary substrate. ACS Nano 7, 8809–8815 (2013).
Ninomiya, N. et al. Fabrication of high-k/metal-gate MoS2 field-effect transistor by device isolation process utilizing Ar-plasma etching. J. Appl. Phys. Jpn 54, 046502 (2015).
Choi, K. et al. Trap density probing on top-gate MoS2 nanosheet field-effect transistors by photo-excited charge collection spectroscopy. Nanoscale 7, 5617 (2015).
Auth, C. et al. A 22nm high performance and low-power CMOS technology featuring fully-depleted tri-gate transistors, self-aligned contacts and high density MIM capacitors. In Proc. 2012 Symposium on VLSI Technology (VLSIT) 131–132 (IEEE, 2012).
Wang, L. et al. One-dimensional electrical contact to a two-dimensional material. Science 342, 614–617 (2013).
Takahashi, N. & Nagashio, K. Buffer layer engineering on graphene via various oxidation methods for atomic layer deposition. Appl. Phys. Express 9, 125101 (2016).
Xia, J., Chen, F., Li, J. & Tao, N. Measurement of the quantum capacitance of graphene. Nat. Nanotechnol. 4, 505–509 (2009).
McPherson, J., Kim, J., Shanware, A. & Mogul, H. Thermochemical description of dielectric breakdown in high dielectric constant materials. Appl. Phys. Lett. 82, 2121–2123 (2003).
Jeong, S. J. et al. Thickness scaling of atomic-layer-deposited HfO2 films and their application to wafer-scale graphene tunnelling transistors. Sci. Rep. 6, 20907 (2016).
Muller, J. et al. Ferroelectricity in simple binary ZrO2 and HfO2. Nano Lett. 12, 4318–4223 (2012).
Gusev, E. P. et al. Ultrathin high-κ gate stacks for advanced CMOS devices. In International Electron Devices Meeting. Technical Digest 20.1.1–20.1.4 (IEEE, 2001).
Zhong, D. et al. Gigahertz integrated circuits based on carbon nanotube films. Nat. Electron. 1, 40–45 (2018).
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.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
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). https://doi.org/10.1038/s41928-019-0334-y
Nature Electronics (2022)
Nature Electronics (2022)
Nano Research (2022)
Nano Research (2022)