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Photocurrent measurements of supercollision cooling in graphene


The cooling of hot electrons in graphene is the critical process underlying the operation of exciting new graphene-based optoelectronic and plasmonic devices, but the nature of this cooling is controversial. We extract the hot-electron cooling rate near the Fermi level by using graphene as a novel photothermal thermometer that measures the electron temperature (T(t)) as it cools dynamically. We find the photocurrent generated from graphene p–n junctions is well described by the energy dissipation rate CdT/dt = −A(T3Tl3), where the heat capacity is C = α T and Tl is the base lattice temperature. These results are in disagreement with predictions of electron–phonon emission in a disorder-free graphene system, but in excellent quantitative agreement with recent predictions of a disorder-enhanced supercollision cooling mechanism. We find that the supercollision model provides a complete and unified picture of energy loss near the Fermi level over the wide range of electronic (15 to 3,000 K) and lattice (10–295 K) temperatures investigated.

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Figure 1: Hot-electron cooling by acoustic phonons.
Figure 2: Photocurrent set-up, a time-resolved graphene thermometer.
Figure 3: PC response obeys SC power laws.
Figure 4: Extracting the hot-electron relaxation time.
Figure 5: SC model predicts TPC dependence on Tl.

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  1. Viljas, J. K. & Heikkilä, T. T. Electron-phonon heat transfer in monolayer and bilayer graphene. Phys. Rev. B 81, 245404 (2010).

    Article  ADS  Google Scholar 

  2. Tse, W-K. & Das Sarma, S. Energy relaxation of hot Dirac fermions in graphene. Phys. Rev. B 79, 235406 (2009).

    Article  ADS  Google Scholar 

  3. Bistritzer, R. & MacDonald, A. H. Electronic cooling in graphene. Phys. Rev. Lett. 102, 206410 (2009).

    Article  ADS  Google Scholar 

  4. Kubakaddi, S. S. Interaction of massless Dirac electrons with acoustic phonons in graphene at low temperatures. Phys. Rev. B 79, 075417 (2009).

    Article  ADS  Google Scholar 

  5. Malic, E., Winzer, T., Bobkin, E. & Knorr, A. Microscopic theory of absorption and ultrafast many-particle kinetics in graphene. Phys. Rev. B 84, 205406 (2011).

    Article  ADS  Google Scholar 

  6. Song, J. C. W., Reizer, M. Y. & Levitov, L. S. Supercollisions and the bottleneck for electron-lattice cooling in graphene. Phys. Rev. Lett. 109, 106602 (2012).

    Article  ADS  Google Scholar 

  7. Sun, D. et al. Hot carrier cooling by acoustic phonons in epitaxial graphene by ultrafast pump–probe spectroscopy. Phys. Status Solidi C 8, 1194–1197 (2011).

    Article  ADS  Google Scholar 

  8. Mueller, T., Xia, F. & Avouris, P. Graphene photodetectors for high-speed optical communications. Nature Photon. 4, 297–301 (2010).

    Article  Google Scholar 

  9. Lemme, M. C. et al. Gate-activated photoresponse in a graphene pn junction. Nano Lett. 11, 4134–4137 (2011).

    Article  ADS  Google Scholar 

  10. Bonaccorso, F., Sun, Z., Hasan, T. & Ferrari, A. C. Graphene photonics and optoelectronics. Nature Photon. 4, 611–622 (2010).

    Article  ADS  Google Scholar 

  11. Yan, J. et al. Dual-gated bilayer graphene hot-electron bolometer. Nature Nanotech. (2012).

  12. Fong, K. C. & Schwab, K. C. Ultrasensitive and wide-bandwidth thermal measurements of graphene at low temperatures. Phys. Rev. X 3, 031006 (2012).

    Google Scholar 

  13. Breusing, M., Ropers, C. & Elsaesser, T. Ultrafast carrier dynamics in graphite. Phys. Rev. Lett. 102, 086809 (2009).

    Article  ADS  Google Scholar 

  14. Meric, I. et al. Current saturation in zero-bandgap, top-gated graphene field-effect transistors. Nature Nanotech. 3, 654–659 (2008).

    Article  ADS  Google Scholar 

  15. Gabor, N. M. et al. Hot carrier assisted intrinsic photoresponse in graphene. Science 334, 648–652 (2011).

    Article  ADS  Google Scholar 

  16. Song, J. C. W., Rudner, M. S., Marcus, C. M. & Levitov, L. S. Hot carrier transport and photocurrent response in graphene. Nano Lett. 11, 4688–4692 (2011).

    Article  ADS  Google Scholar 

  17. Xu, X., Gabor, N. M., Alden, J. S., van der Zande, A. M. & McEuen, P. L. Photo-thermoelectric effect at a graphene interface junction. Nano Lett. 10, 562–566 (2009).

    Article  ADS  Google Scholar 

  18. Sun, D. et al. Ultrafast hot-carrier-dominated photocurrent in graphene. Nature Nanotech. 7, 114–118 (2012).

    Article  ADS  Google Scholar 

  19. Wang, H. et al. Ultrafast relaxation dynamics of hot optical phonons in graphene. Appl. Phys. Lett. 96, 081917 (2010).

    Article  ADS  Google Scholar 

  20. Urich, A., Unterrainer, K. & Mueller, T. Intrinsic response time of graphene photodetectors. Nano Lett. 7, 2804 (2011).

    Article  ADS  Google Scholar 

  21. Strait, J. H. et al. Very slow cooling dynamics of photoexcited carriers in graphene observed by optical-pump terahertz-probe spectroscopy. Nano Lett. 11, 4902–4906 (2011).

    Article  ADS  Google Scholar 

  22. Winnerl, S. et al. Carrier relaxation in epitaxial graphene photoexcited near the dirac point. Phys. Rev. Lett. 107, 237401 (2011).

    Article  ADS  Google Scholar 

  23. Li, X. et al. Large-area synthesis of high-quality and uniform graphene films on copper foils. Science 324, 1312–1314 (2009).

    Article  ADS  Google Scholar 

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This research was supported by the Kavli Institute at Cornell for Nanoscale Science (KIC), AFOSR (FA 9550-10-1-0410), by the NSF through the Center for Nanoscale Systems and by the MARCO Focused Research Center on Materials, Structures, and Devices. We thank J. Song, K. McGill and J. Kevek for their helpful contributions. Device fabrication was performed at the Cornell Nanofabrication Facility/National Nanofabrication Infrastructure Network.

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The experiment was built by M.W.G. and measurements performed by M.W.G. and S-F.S. Graphene devices were fabricated by S-F.S. Theory and data analysis was performed by M.W.G. and P.L.M. All authors participated in the elaboration of the research project.

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Correspondence to Matt W. Graham or Paul L. McEuen.

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The authors declare no competing financial interests.

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Graham, M., Shi, SF., Ralph, D. et al. Photocurrent measurements of supercollision cooling in graphene. Nature Phys 9, 103–108 (2013).

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