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Current saturation in zero-bandgap, top-gated graphene field-effect transistors

Abstract

The novel electronic properties of graphene1,2,3,4, including a linear energy dispersion relation and purely two-dimensional structure, have led to intense research into possible applications of this material in nanoscale devices. Here we report the first observation of saturating transistor characteristics in a graphene field-effect transistor. The saturation velocity depends on the charge-carrier concentration and we attribute this to scattering by interfacial phonons in the SiO2 layer supporting the graphene channels5,6. Unusual features in the current–voltage characteristic are explained by a field-effect model and diffusive carrier transport in the presence of a singular point in the density of states. The electrostatic modulation of the channel through an efficiently coupled top gate yields transconductances as high as 150 µS µm−1 despite low on–off current ratios. These results demonstrate the feasibility of two-dimensional graphene devices for analogue and radio-frequency circuit applications without the need for bandgap engineering.

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Figure 1: Basic top-gated graphene FET design.
Figure 2: Current–voltage characteristics of the GFET device.
Figure 3: Kink effect in GFET devices.
Figure 4: Field-effect modelling of the GFET device.

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Acknowledgements

We thank N. Baklitskaya for her help with the device fabrication. This work was supported by the Semiconductor Research Corporation Focus Centre Research Program through both the Centre for Circuit and Systems Solutions and the Centre on Functional Engineered Nano Architectonics and the US Office of Naval Research grant no. N000150610138.

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Authors and Affiliations

Authors

Contributions

I.M. and K.L.S. designed the experiments. I.M. performed the experiments and analysed the data. M.Y.H., A.F.Y. and P.K. assisted with data analysis. B.O. assisted with device fabrication. I.M. and K.L.S. co-wrote the paper. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Kenneth L. Shepard.

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Meric, I., Han, M., Young, A. et al. Current saturation in zero-bandgap, top-gated graphene field-effect transistors. Nature Nanotech 3, 654–659 (2008). https://doi.org/10.1038/nnano.2008.268

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