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We had earlier shown [1,2] that electrochemical gating of the single and bilayer graphene transistors allows astudy of G-phonon renormalization at high carrier densities by in-situ Raman scattering. In this talk we will presentour recent studies of simultaneous p and n – type carrier injection [3,4] and associated spatially resolved Ramanexperiments [5] to quantify the variation of doping across the graphene channel. We will also present Ramanmeasurements of the highly dispersive D and 2D modes using different laser energies at various doping levels [5].
[1]. A. Das, S. Pisana, B. Piscanec, B. Chakraborty, S. R. Saha, U.V. Waghmare, R. Yiang, H.R. Krishnamurthy, A.K. Geim, A.C. Ferrari and A.K. Sood; Electrochemically Top Gated Graphene: Monitoring Dopants by Raman Scattering, Nature Nanotechnology 3, 210 - 215 (2008).
[2]. A. Das, B. Chakraborty, S. Piscanec, S. Pisana, A.K. Sood and A.C. Ferrari; Phonon renormalization in doped bilayer graphene, Phys. Rev. B 79, 155417 (2009).
[3]. B.Chakraborty, A. Das and A.K. Sood, Formation of p-n junction in polymer electrolyte – top gated bilayer graphene transistor, Nanotechnology 20, 365203 (2009).
[4]. K S Vasu, Biswanath Chakraborty, S Sampath and A.K. Sood, Probing top-gated field effect transistor of reduced graphene oxide monolayer made by dielectrophoresis, Solid State Communication 150, 1295-1298 (2010).
[5]. B. Chakraborty and A.K. Sood (2010).
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