Hot carrier relaxation of Dirac fermions in bilayer epitaxial graphene
Journal article, 2015
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-Gruneisen power-law behaviour of T-4 at carrier temperatures from 1.4K up to similar 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 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.
energy loss rate
hot carriers
bilayer graphene
magnetotransport
Author
J. Huang
University of Oxford
J. A. Alexander-Webber
University of Oxford
Tjbm Janssen
National Physical Laboratory
A.Y. Tzalenchuk
Royal Holloway University of London
National Physical Laboratory
Thomas Yager
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Samuel Lara Avila
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Sergey Kubatkin
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
R. L. Myers-Ward
Naval Research Laboratory
V. D. Wheeler
Naval Research Laboratory
D. K. Gaskill
Naval Research Laboratory
R. J. Nicholas
University of Oxford
Journal of Physics Condensed Matter
0953-8984 (ISSN)
Vol. 27 16 164202Graphene-Based Revolutions in ICT And Beyond (Graphene Flagship)
European Commission (FP7) (EC/FP7/604391), 2013-10-01 -- 2016-03-31.
Subject Categories (SSIF 2011)
Condensed Matter Physics
DOI
10.1088/0953-8984/27/16/164202