▎ 摘　　要

The electronic band structure of graphene is strongly dependent on the amount of strain and/or doping present. We performed a comprehensive study of temperature-dependent strain and doping in isotopically labeled graphene mono-and bilayers on a SiO2/Si substrate by Raman spectral mapping at well-defined temperatures between 300 and 10K. The principal Raman active modes of the graphene (G, 2D) were subjected to correlation analysis, which enabled reliable separation of the strain and doping contributions. The influence of strain on the monolayer and top and bottom layers of the bilayer graphene is large and shows a pronounced temperature-dependent variation. A clear difference is observed in local strain fluctuations on length scales much smaller than the laser spot. In both the monolayer and the bottom layer of the bilayer, which are in contact with the substrate, a significant amount of local strain is induced when the temperature is varied. In contrast, the influence of local strain on the top layer of the bilayer is much smaller. Temperature dependence of the doping is clearly present in both layers, suggesting equalization of the captured charge in the bilayer down to low temperatures.