Raman mapping investigation of graphene on transparent flexible substrate: The strain effect

We report a Raman mapping investigation of strain effects on graphene on transparent and flexible substrate. Raman mappings reveal a significant red-shift of the 2D mode with introduction of tensile strain, distribution of local strain in the strained graphene, and immediate recovery after strain relaxation. The systematic fitting and statistical analysis quantify the tensile strain sensitivity of graphene, which is comparable to the single-walled carbon nanotubes (SWNTs) and implies the potential of graphene as an ultrasensitive strain sensor. The uniaxial strain will break the sublattice symmetry of graphene, hence changing its electronic band structures, for example, bandgap opening. This suggests the potential to desirably tune electronic band structures of graphene by controllably introducing strain.