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arXiv · 1409.6267

Hot carrier relaxation of Dirac fermions in bilayer epitaxial graphene

J. Huang·J. A. Alexander-Webber·T. J. B. M. Janssen·A. Tzalenchuk·T. Yager·S. Lara-Avila·S. Kubatkin·R. L. Myers-Ward·V. D. Wheeler·D. K. Gaskill·R. J. Nicholas
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Abstract

Energy relaxation of hot Dirac fermions in bilayer epitaxial graphene is experimentally investigated by magnetotransport measurements on Shubnikov-de Haas oscillations and weak localization. The hot-electron energy loss rate is found to follow the predicted Bloch-Gr\"uneisen power-law behaviour of $T^4$ at carrier temperatures from 1.4 K up to $\sim$100 K, due to electron-acoustic phonon interactions with a deformation potential coupling constant of 22 eV. A carrier density dependence $n_e^{-1.5}$ in the scaling of the $T^4$ power law is observed in bilayer graphene, in contrast to the $n_e^{-0.5}$ dependence in monolayer graphene, leading to a crossover in the energy loss rate as a function of carrier density between these two systems. The electron-phonon relaxation time in bilayer graphene is also shown to be strongly carrier density dependent, while it remains constant for a wide range of carrier densities in monolayer graphene. Our results and comparisons between the bilayer and monolayer exhibit a more comprehensive picture of hot carrier dynamics in graphene systems.

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J. Huang, J. A. Alexander-Webber, T. J. B. M. Janssen, A. Tzalenchuk, T. Yager, S. Lara-Avila, S. Kubatkin, R. L. Myers-Ward, V. D. Wheeler, D. K. Gaskill, R. J. Nicholas. 2014-09-22. Hot carrier relaxation of Dirac fermions in bilayer epitaxial graphene. https://doi.org/10.1088/0953-8984/27/16/164202

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