Tension-Induced Raman Spectrum Enhanced Phenomena of Graphene Membrane

In the Letter, we reported the tension-induced Raman spectrum enhanced phenomena of graphene membrane. The standard micro-fabrication processes are utilized to fabricate micro-scale holes on Silicon-On-Insulator (SOI) wafers, and suspended graphene membranes are transferred onto target substrates with shallow holes and flat substrates using the dry and wet transfer techniques, respectively. The corrugated graphene near the hole is stretched smoothly due to the built-in strain during the transfer processes, and the intensity ratio between the 2D and G bands I_2D/I_G>5, which demonstrates the high quality of graphene sheet is obtained under the stretching stress. The intensity ratio between the 2D and G bands would diminish greatly when the graphene membrane is broken. Therefore, the Raman spectrum intensities of graphene membranes can be tuned by the built-in strain. The study can be helpful for further understanding the formation mechanism of corrugated graphene, the suppressing method of the small ripple in graphene, and the way to improve the quality of graphene.