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arXiv · 1005.2293

Probing the electron-phonon coupling in ozone-doped graphene by Raman spectroscopy

F. Alzina·H. Tao·J. Moser·Y. Garcia·A. Bachtold·C. M. Sotomayor-Torres
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Abstract

We have investigated the effects of ozone treatment on graphene by Raman scattering. Sequential ozone short-exposure cycles resulted in increasing the $p$ doping levels as inferred from the blue shift of the 2$D$ and $G$ peak frequencies, without introducing significant disorder. The two-phonon 2$D$ and 2$D'$ Raman peak intensities show a significant decrease, while, on the contrary, the one-phonon G Raman peak intensity remains constant for the whole exposure process. The former reflects the dynamics of the photoexcited electrons (holes) and, specifically, the increase of the electron-electron scattering rate with doping. From the ratio of 2$D$ to 2$D$ intensities, which remains constant with doping, we could extract the ratio of electron-phonon coupling parameters. This ratio is found independent on the number of layers up to ten layers. Moreover, the rate of decrease of 2$D$ and 2$D'$ intensities with doping was found to slowdown inversely proportional to the number of graphene layers, revealing the increase of the electron-electron collision probability.

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F. Alzina, H. Tao, J. Moser, Y. Garcia, A. Bachtold, C. M. Sotomayor-Torres. 2010-05-13. Probing the electron-phonon coupling in ozone-doped graphene by Raman spectroscopy. https://doi.org/10.1103/physrevb.82.075422

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