Raman spectroscopy of graphene under ultrafast laser excitation.


Type
Article
Change log
Authors
Ferrante, C 
Virga, A 
Martinati, M 
De Fazio, D 
Abstract

The equilibrium optical phonons of graphene are well characterized in terms of anharmonicity and electron-phonon interactions; however, their non-equilibrium properties in the presence of hot charge carriers are still not fully explored. Here we study the Raman spectrum of graphene under ultrafast laser excitation with 3 ps pulses, which trade off between impulsive stimulation and spectral resolution. We localize energy into hot carriers, generating non-equilibrium temperatures in the ~1700-3100 K range, far exceeding that of the phonon bath, while simultaneously detecting the Raman response. The linewidths of both G and 2D peaks show an increase as function of the electronic temperature. We explain this as a result of the Dirac cones' broadening and electron-phonon scattering in the highly excited transient regime, important for the emerging field of graphene-based photonics and optoelectronics.

Description
Keywords
cond-mat.mes-hall, cond-mat.mes-hall, physics.optics
Journal Title
Nat Commun
Conference Name
Journal ISSN
2041-1723
2041-1723
Volume Title
9
Publisher
Springer Science and Business Media LLC
Sponsorship
Engineering and Physical Sciences Research Council (EP/K01711X/1)
Engineering and Physical Sciences Research Council (EP/K017144/1)
Engineering and Physical Sciences Research Council (EP/L016087/1)
EPSRC (via University of Manchester) (R119256)
EPSRC (1354817)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (696656)