Improved method for measuring crystal orientation of strained graphene using polarization dependence of Raman G band and 2D bands

The electron behavior in graphene is described by the Dirac equation, which gives graphene the unique property of generating a pseudo-field due to the lattice strain. The pseudo-magnetic field is predicted theoretically to induce phenomena such as band gap formation and electron confinement. On the other hand, such strain-induced phenomena are strongly dependent on the direction of strain. Therefore, it is important to accurately measure the crystal orientation and the strain direction in order to study the strain-related phenomena in graphene. However, in conventional methods for measuring crystal orientation of strained graphene using the polarization dependence of the Raman G-band position, the obtained strain angles include systematic errors due to the misorientation of the sample with respect to the Raman device system. In this study, we developed a method to obtain both the strain direction and the polarizer angle simultaneously from the polarized Raman spectroscopy of the G and 2D bands.