posted on 2021-09-16, 14:37authored byStavros Katsiaounis, Andrey V. Sharkov, Eugeniy V. Khoroshilov, Georgios Paterakis, John Parthenios, Konstantinos Papagelis
Phonon
lifetimes are fundamental physical parameters playing a
significant role in phonon transport and thermal conductivity of two-dimensional
materials. We employed the time-resolved incoherent anti-Stokes Raman
scattering (TRIARS) technique to capture the G phonon dynamics and
to extract the G phonon lifetimes in supported exfoliated and polycrystalline
chemical vapor deposited (CVD) graphene samples of various thickness.
We have found that substrate reduces considerably the G phonon lifetime
of exfoliated monolayer graphene while the corresponding lifetimes
for bilayer and trilayer converge gradually close to that of graphite.
The lifetimes of CVD monolayers are systematically lower than exfoliated
ones mainly due to the presence of various types of structural defects.
Besides, the electron–phonon coupling strength of graphite
is determined to be 10.6 cm–1, in excellent agreement
with theoretical predictions for graphene, justifying that the lifetimes
of suspended graphene and graphite are similar.