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Ultrafast graphene photodetector


Graphene research so far has focused on electronic1,2,3,4,5,6 rather than photonic applications, in spite of its impressive optical properties7,8. These include its ability to absorb 2% of incident light over a broad wavelength range despite being just one atom thick7. Here, we demonstrate ultrafast transistor-based photodetectors made from single- and few-layer graphene. The photoresponse does not degrade for optical intensity modulations up to 40 GHz, and further analysis suggests that the intrinsic bandwidth may exceed 500 GHz. The generation and transport of photocarriers in graphene differ fundamentally from those in photodetectors made from conventional semiconductors as a result of the unique photonic and electronic properties of the graphene. This leads to a remarkably high bandwidth, zero source–drain bias and dark current operation, and good internal quantum efficiency.

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Figure 1: Electrical characterizations of the graphene photodetector.
Figure 2: Optical characterizations of the graphene photodetector.
Figure 3: Graphene photodetector circuit model and analysis.


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The authors are grateful to M. Freitag and Z. Chen for helpful discussions, to Y. Vlasov, S. Assefa, W. Green, C. Schow and L. Schares for help with the radio-frequency measurements, to J. Tsang for Raman measurements, and to B. Ek and J. Bucchignano for technical assistance. F.X. is indebted to C.Y. Sung for his encouragement. T.M. acknowledges financial support by the Austrian Science Fund FWF (Erwin Schrödinger fellowship J2705-N16).

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Correspondence to Fengnian Xia or Phaedon Avouris.

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Xia, F., Mueller, T., Lin, Ym. et al. Ultrafast graphene photodetector. Nature Nanotech 4, 839–843 (2009).

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