Vertical transistors—in which the channel length is determined by the thickness of the semiconductor—are of interest in the development of next-generation electronic devices. However, short-channel vertical devices are difficult to fabricate, because the high-energy metallization process typically results in damage to the contact region. Here we show that molybdenum disulfide (MoS2) vertical transistors with channel lengths down to one atomic layer can be created using a low-energy van der Waals metal integration technique. The approach uses prefabricated metal electrodes that are mechanically laminated and transferred on top of MoS2/graphene vertical heterostructures, leading to vertical field-effect transistors with on–off ratios of 26 and 103 for channel lengths of 0.65 nm and 3.60 nm, respectively. Using scanning tunnelling microscopy and low-temperature electrical measurements, we show that the improved electrical performance is the result of a high-quality metal–semiconductor interface, with minimized direct tunnelling current and Fermi-level pinning effect. The approach can also be extended to other layered materials (tungsten diselenide and tungsten disulfide), resulting in sub-3-nm p-type and n-type vertical transistors.
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The data that support the findings of this study are available from the corresponding author upon reasonable request.
Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013).
Chhowalla, M., Jena, D. & Zhang, H. Two-dimensional semiconductors for transistors. Nat. Rev. Mater. 1, 16052 (2016).
Fiori, G. et al. Electronics based on two-dimensional materials. Nat. Nanotechnol. 9, 768–779 (2014).
Allain, A., Kang, J., Banerjee, K. & Kis, A. Electrical contacts to two-dimensional semiconductors. Nat. Mater. 14, 1195–1205 (2015).
Liu, Y. et al. Van der Waals heterostructures and devices. Nat. Rev. Mater. 1, 16042 (2016).
Novoselov, K. S., Mishchenko, A., Carvalho, A. & Castro Neto, A. 2D materials and van der Waals heterostructures. Science 353, aac9439 (2016).
Schwierz, F., Pezoldt, J. & Granzner, R. Two-dimensional materials and their prospects in transistor electronics. Nanoscale 7, 8261–8283 (2015).
Liu, Y. et al. Maximizing the current output in self-aligned graphene–InAs–metal vertical transistors. ACS Nano 13, 847–854 (2019).
Lemaitre, M. G. et al. Improved transfer of graphene for gated Schottky-junction, vertical, organic, field-effect transistors. ACS Nano 6, 9095–9102 (2012).
Georgiou, T. et al. Vertical field-effect transistor based on graphene–WS2 heterostructures for flexible and transparent electronics. Nat. Nanotechnol. 8, 100–103 (2013).
Heo, J. et al. Graphene and thin-film semiconductor heterojunction transistors integrated on wafer scale for low-power electronics. Nano Lett. 13, 5967–5971 (2013).
Yu, W. J. et al. Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters. Nat. Mater. 12, 246–252 (2013).
Moriya, R. et al. Large current modulation in exfoliated-graphene/MoS2/metal vertical heterostructures. Appl. Phys. Lett. 105, 083119 (2014).
Britnell, L. et al. Field-effect tunneling transistor based on vertical graphene heterostructures. Science 335, 947–950 (2012).
Hlaing, H. et al. Low-voltage organic electronics based on a gate-tunable injection barrier in vertical graphene-organic semiconductor heterostructures. Nano Lett. 15, 69–74 (2015).
Lee, I. et al. Ultrahigh gauge factor in graphene/MoS2 heterojunction field effect transistor with variable Schottky barrier. ACS Nano 13, 8392–8400 (2019).
Liu, Y., Duan, X., Huang, Y. & Duan, X. Two-dimensional transistors beyond graphene and TMDCs. Chem. Soc. Rev. 47, 6388–6409 (2018).
Liu, Y. et al. High-current-density vertical-tunneling transistors from graphene/highly doped silicon heterostructures. Adv. Mater. 28, 4120–4125 (2016).
Liu, Y. et al. Toward barrier free contact to molybdenum disulfide using graphene electrodes. Nano Lett. 15, 3030–3034 (2015).
Liu, Y. et al. Highly flexible electronics from scalable vertical thin film transistors. Nano Lett. 14, 1413–1418 (2014).
Yu, W. J. et al. Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials. Nat. Nanotechnol. 8, 952–958 (2013).
Liu, Y. et al. High-performance organic vertical thin film transistor using graphene as a tunable contact. ACS Nano 9, 11102–11108 (2015).
Choi, Y. et al. Low-voltage complementary electronics from ion-gel-gated vertical van der Waals heterostructures. Adv. Mater. 28, 3742–3748 (2016).
Liu, Y., Huang, Y. & Duan, X. Van der Waals integration before and beyond two-dimensional materials. Nature 567, 323–333 (2019).
Kang, J. et al. Probing out-of-plane charge transport in black phosphorus with graphene-contacted vertical field-effect transistors. Nano Lett. 16, 2580–2585 (2016).
He, D. et al. Two-dimensional quasi-freestanding molecular crystals for high-performance organic field-effect transistors. Nat. Commun. 5, 5162 (2014).
Yang, H. et al. Graphene barristor, a triode device with a gate-controlled Schottky barrier. Science 336, 1140–1143 (2012).
Choi, Y. J. et al. Remote gating of Schottky barrier for transistors and their vertical integration. ACS Nano 13, 7877–7885 (2019).
Jung, Y. et al. Transferred via contacts as a platform for ideal two-dimensional transistors. Nat. Electron. 2, 187–194 (2019).
Wang, Y. et al. Van der Waals contacts between three-dimensional metals and two-dimensional semiconductors. Nature 568, 70–74 (2019).
Liu, Y. et al. Approaching the Schottky–Mott limit in van der Waals metal–semiconductor junctions. Nature 557, 696–700 (2018).
Horri, A., Faez, R., Pourfath, M. & Darvish, G. A computational study of vertical tunneling transistors based on graphene-WS2 heterostructure. J. Appl. Phys. 121, 214503 (2017).
Das, T. et al. Vertical field effect tunneling transistor based on graphene-ultrathin Si nanomembrane heterostructures. 2D Mater. 2, 044006 (2015).
Y.L. acknowledges financial support from the National Natural Science Foundation of China (grant nos. 51991340, 51991341, 51802090 and 61874041) and from the Hunan Science Fund for Excellent Young Scholars (grant no. 812019037). L. Liao acknowledges financial support from the National Key Research and Development Program of China (grant no. 2018YFA0703704). A.P. acknowledges financial support from the National Natural Science Foundation of China (grant nos. 62090035 and U19A2090).
The authors declare no competing interests.
Peer review information Nature Electronics thanks PingAn Hu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Liu, L., Kong, L., Li, Q. et al. Transferred van der Waals metal electrodes for sub-1-nm MoS2 vertical transistors. Nat Electron 4, 342–347 (2021). https://doi.org/10.1038/s41928-021-00566-0
Nature Electronics (2021)