Probing substrate influence on graphene by fitting Raman signals with Voigt profile

We provide a new approach to identify the substrate influence and doping effect on graphene surface. In this work, the Raman bandwidths of G bands were fitted into the Voigt profile. The bandwidths of Lorentzian parts were kept as constant whether it is the suspended and supported graphene. For the Gaussian part, the suspended graphene exhibit a much greater Gaussian bandwidths of than supported graphene. It reveals the doping effect on supported graphene is stronger than that of suspended graphene. We also analyze the peak-positions of G bands, and I_2D/I_G ratios. For the suspended graphene, the peak positions of G band are downshifted respect to supported graphene, and the I_2D/I_G ratios of suspended graphene are larger than those of supported graphene.