Ferroelectric tunnel junctions use a thin ferroelectric layer as a tunnelling barrier, the height of which can be modified by switching its ferroelectric polarization. The junctions can offer low power consumption, non-volatile switching and non-destructive readout, and thus are promising for the development of memory and computing applications. However, achieving a high tunnelling electroresistance (TER) in these devices remains challenging. Typical junctions, such as those based on barium titanate or hafnium dioxide, are limited by their small barrier height modulation of around 0.1 eV. Here, we report a ferroelectric tunnel junction that uses layered copper indium thiophosphate (CuInP2S6) as the ferroelectric barrier, and graphene and chromium as asymmetric contacts. The ferroelectric field effect in CuInP2S6 can induce a barrier height modulation of 1 eV in the junction, which results in a TER of above 107. This modulation, which is shown using Kelvin probe force microscopy and Raman spectroscopy, is due to the low density of states and small quantum capacitance near the Dirac point of the semi-metallic graphene.
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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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J.W., H.-Y.C. and H.W. acknowledge support from the Army Research Office Young Investigator Program (grant W911NF-18-1-0268) and the National Science Foundation (grant CCF-1618038). N.Y. and J.G. acknowledge support from the National Science Foundation (grants 1618762, 1610387 and 1904580). J.C. and X.L. acknowledge support from the Semiconductor Research Corporation (SRC).
The authors declare no competing interests.
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Wu, J., Chen, H., Yang, N. et al. High tunnelling electroresistance in a ferroelectric van der Waals heterojunction via giant barrier height modulation. Nat Electron 3, 466–472 (2020). https://doi.org/10.1038/s41928-020-0441-9
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