Abstract
Achieving low contact resistance is a critical challenge in the development of p-type transistors that use monolayer transition metal dichalcogenides, such as tungsten diselenide (WSe2), as their channel material. Contacts made with high work function metals require deposition at high temperatures, which typically creates defects or strain at the metal–channel interface. One solution is to use metallic two-dimensional (2D) materials that have atomically flat surfaces and can be deposited at low temperatures, as have been reported for n-type semiconductors. However, the comparatively large bandgap of WSe2 has hindered experimental progress with p-type transistors. Here we show that metallic layered Nb0.3W0.7Se2 can be used to create contacts for monolayer and bilayer WSe2 field-effect transistors with channel lengths down to 100 nm. Our 2D–2D contacted field-effect transistors exhibit on-current densities of up to 358 µA µm−1 and 1.1 mA µm−1 on monolayer and bilayer WSe2 channels, respectively. In combination with scaled gate dielectrics (effective oxide thickness of 1.3 nm), the fabricated 2D–2D contacted monolayer WSe2 devices achieve a subthreshold swing of 88 mV dec−1.
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Acknowledgements
Z.S., P.W., R.T., J.C., H.-Y.L., Y.T., Z.C. and J.A. acknowledge support from Intel Corporation. A.A. acknowledges the Imec Industrial Affiliation Program for funding. S.K. and A.V.D. acknowledge support from the Material Genome Initiative funding allocated to NIST. H.Z. acknowledges support from NIST under the financial assistance grant no. 70NANB22H101. Certain commercial equipment, instruments, software or materials are identified in this paper to specify the experimental procedure adequately. Such identifications are not intended to imply recommendation or endorsement by NIST, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose.
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Z.S. designed the experiments, fabricated the devices and performed the electrical measurements. A.A. developed the simulation code, designed and performed the first-principle simulations and quantum transport simulations and analysed the simulation data. Z.S. and P.W. analysed the results and experimental plans. Z.S., A.A. and J.A. wrote the paper. H.Z., A.D. and Y.T. performed the electron miscopy experiments. S.K. and A.D. grew the materials. Z.S., A.A., P.W., R.T., J.C., H.-Y.L., Z.C., G.P. and J.A. analysed the data, discussed the results and agreed on their implications.
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Extended data
Extended Data Fig. 1 Transfer characteristics of mechanically exfoliated NbxW1-xSe2 flakes of varied composition with different thicknesses.
a, Schematic of Nbx1W1-x1Se2 transistors, it had a near-zero Nb concentration, undetectable by EDX as described in the materials growth part of the Method section. b-e, Transfer characteristics of different Nbx1W1-x1Se2 flake thickness. f, Schematic of Nb0.03W0.97Se2 transistors. g-j, Transfer characteristics of different Nb0.03W0.97Se2 flake thickness. k, Schematic of Nb0.3W0.7Se2 transistors. l-o, Transfer characteristics of different Nb0.3W0.7Se2 flake thickness.
Extended Data Fig. 2 Output characteristics of 2D/2D contacted ML FETs on 90 nm SiO2 substrates.
a-d, four different 2D/2D contacted devices with a channel length of 200 nm. e, a 2D/2D contacted device with a channel length of 400 nm. f and g, two 2D/2D contacted devices with a channel length of 1 um. h, a 2D/2D contacted device with a channel length of 2 um.
Extended Data Fig. 3 DFT-NEGF-simulated spectral current (in absolute units), | J(E)|, along the transport direction (x) in the Nb0.3W0.7Se2/WSe2 heterostructure of Fig. 4c for different NA,WSe2 doping concentrations in the WSe2 bottom layer a. NA,WSe2 = 3×1012 cm−2, b. NA,WSe2 = 6×1012 cm−2, and c. NA,WSe2 = 1.8×1013 cm−2.
The valence band in the WSe2 layer, EV,WSe2, as well as, the source Fermi level in the Nb0.3W0.7Se2 metallic region (black dotted line), EFS, metal, are also indicated. The x-distance between the end of the EFS,metal line and the EV,WSe2 line in the vicinity of the source Fermi level Lt,SBH is indicated with a blue arrow in a. Lt,SBH represents an estimate of the carrier tunneling distance through the Schottky barrier. As NA,Wse2 is increased, this distance is strongly reduced b, or vanishes c, that is, the carriers feel an increasingly transparent Schottky barrier when crossing from the edge of the metal layer to the WSe2 layer. Finally, the position of the neutrality level, EN,metal, that is, the equilibrium DFT- Fermi-level moved by the self-consistent potential in the metal layer is also shown, as well as a schematic view of the device, with the top metal and bottom WSe2 positions in the x-direction matching those of the spectral plot. VDS = −0.15 V.
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Sun, Z., Afzalian, A., Wu, P. et al. Low-resistance contacts for p-type monolayer tungsten diselenide transistors using metallic layered Nb0.3W0.7Se2. Nat Electron (2026). https://doi.org/10.1038/s41928-026-01568-6
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DOI: https://doi.org/10.1038/s41928-026-01568-6
