Invité par Denis Fichou Graphene – a two dimensional monolayer of Carbon atoms is the most recent addition to the family of low-dimensional carbon, namely one-dimensional nanotubes and zero-dimensional fullerenes. After reviewing why graphene is so exciting, we will focus on our on-going work on single and bilayer graphene, with specific goals to understand phonons and Raman signatures of these systems [1]. The controlled doping of graphene is achieved by electrochemical top gated field effect transistor using solid polymer electrolyte [2, 3]. In-situ studies of phonons in single and bilayer graphene as a function of doping provide us with a measure of electron-phonon coupling in these systems. The results are quantitatively explained using ab-initio calculations that take into account effects beyond adiabatic approximation. An interesting comparison of graphene is made with our recent work on doped single wall carbon nanotubes [4]. [1] Raman Spectroscopy of graphene on different substrates and influence of defects; Anindya. Das, B. Chakraborty and A. K. Sood. Cond-mat.arXiv: 0710.4160 (October 2007), Bull.Mat. Science 31, 1-6 (2008) [2] Monitoring Dopants by Raman Scattering in Top Gated Graphene transistor ; Anindya. Das, S. Pisana, B. Chakraborty, S. Piscanec, S. K. Saha, U. V. Waghmare, R. Yiang, H. R. Krishnamurhthy, A. K. Geim, A. C. Ferrari and A. K. Sood; Nature Nanotechnology 3, 210 – 215 (2008). [3] Phonon renormalization is doped bilayer graphene, Anindya Das, B. Chakraborty, S. Pisana, A. C. Ferrari and A.K. Sood (2008). [4] Doping in Carbon Nanotubes Probed by Raman and Transport Measurements; Anindya Das, A. K. Sood, A. Govindaraj, A. Marco Saitta, Michele Lazzeri, Francesco Mauri and C. N. R Rao, Phys. Rev. Lett. 99, 136803 (2007).
Indian Institute of Science (IISc) Bangalore