Two-probe study of hot carriers in reduced graphene oxide

Journal of Applied Physics (Impact Factor: 2.18). 03/2011; 109(8). DOI: 10.1063/1.3573674
Source: arXiv


The energy relaxation of carriers in reduced graphene oxide thin films is
studied using optical pump-probe spectroscopy with two probes of different
colors. We measure the time difference between peaks of the carrier density at
each probing energy by measuring a time-resolved differential transmission and
find that the carrier density at the lower probing energy peaks later than that
at the higher probing energy. Also, we find that the peak time for the lower
probing energy shifts from about 92 to 37 fs after the higher probing energy
peak as the carrier density is increased from 1.5E12 to 3E13 per square
centimeter, while no noticeable shift is observed in that for the higher
probing energy. Assuming the carriers rapidly thermalize after excitation, this
indicates that the optical phonon emission time decreases from about 50 to
about 20 fs and the energy relaxation rate increases from 4 to 10 meV/fs. The
observed density dependence is inconsistent with the phonon bottleneck effect.

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Available from: Hui Zhao, May 12, 2015
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    • "A large body of experimental work on ultrafast spectroscopy of graphene is available [1] [2] [3] [4] .However, so far, most studies have been performed with a time resolution which is too low to observe e-e scattering dynamics and thus have probed an equilibrated hot electron/hole distribution, established within the pump pulse duration (~100- 150 fs). These studies have revealed the dynamics of carrier cooling through interaction with the lattice. "
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