Frequency shift of optical phonons in doped graphene layers

Abstract

We use first-principles density-functional calculations to determine the frequency shift of the A${}_1^{\prime }$-$\mathbf{K}$ phonon (Raman D band) in monolayer graphene, as a function of the charge doping. A detailed DFT study on the electron-phonon coupling and the phonon line width of E${}_{2g}$-$\mathbf{\Gamma }$ and A${}_1^{\prime }$-$\mathbf{K}$ phonons are also performed for graphene multi-layers. Furthermore, we explain the experimentally observed '1/(Number of Layers)' behaviour of the Raman G band position after including the dynamic response treated within time dependent perturbation theory.

4 pages, 3 figures, 1 table