Hot carrier relaxation of Dirac fermions in bilayer epitaxial graphene

J Huang, JA Alexander-Webber… - Journal of Physics …, 2015 - iopscience.iop.org
Journal of Physics: Condensed Matter, 2015iopscience.iop.org
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–
Grüneisen power-law behaviour of T 4 at carrier temperatures from 1.4 K up to∼ 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 …
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–Grüneisen power-law behaviour of T 4 at carrier temperatures from 1.4 K up to∼ 100 K, due to electron-acoustic phonon interactions with a deformation potential coupling constant of 22 eV. A carrier density dependence in the scaling of the T 4 power law is observed in bilayer graphene, in contrast to the 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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