Unsaturated Drift Velocity of Monolayer Graphene

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Title
Unsaturated Drift Velocity of Monolayer Graphene
Author(s)
Hee Jun Shin; Jaesu Kim; Sungho Kim; Homin Choi; Sahnghyub Lee; Young Hee Lee; Joo-Hiuk Son; Seong Chu Lim
Publication Date
2018-03
Journal
NANO LETTERS, v.18, no.3, pp.1575 - 1581
Publisher
AMER CHEMICAL SOC
Abstract
We observe that carriers in graphene can be accelerated to the Fermi velocity without heating the lattice. At large Fermi energy vertical bar E-F vertical bar > 110 meV, electrons excited by a high-power terahertz pulse E-THz relax by emitting optical phonons, resulting in heating of the graphene lattice and optical phonon generation. This is owing to enhanced electron phonon scattering at large Fermi energy, at which the large phase space is available for hot electrons. The emitted optical phonons cause carrier scattering, reducing the drift velocity or carrier mobility. However, for vertical bar E-F vertical bar < 110 meV, electron phonon scattering rate is suppressed owing to the diminishing density of states near the Dirac point. Therefore, E-THz continues to accelerate carriers without them losing energy to optical phonons, allowing the carriers to travel at the Fermi velocity. The exotic carrier dynamics does not result from the massless nature, but the electron-optical-phonon scattering rate depends on Fermi level in the graphene. Our observations provide insight into the application of graphene for high-speed electronics without degrading carrier mobility © 2018 American Chemical Society
URI
https://pr.ibs.re.kr/handle/8788114/4646
ISSN
1530-6984
Appears in Collections:
Center for Integrated Nanostructure Physics(나노구조물리 연구단) > Journal Papers (저널논문)
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