Effects of controllable biaxial strain on the Raman spectra of monolayer graphene prepared by chemical vapor deposition

Controllable biaxial strain is delivered to monolayer graphene prepared by chemical vapor deposition via applying an electric field to the underlying piezoelectric [Pb(Mg1/3Nb2/3)O3]0.7-[PbTiO3]0.3substrate. The effects of tunable strain on the Raman spectra of graphene are investigated in reversible and real-time manners. Such strain can result in a blue shift in 2D band of graphene. The calculations based on the Grüneisen parameter identify the actual biaxial strain to graphene, leading to a continuous 2D band shift, which is detected during the retention of bias voltage. The physical mechanism behind this unique Raman behavior is discussed.