title: Revealing anisotropic strain in exfoliated graphene by polarized Raman spectroscopy.
abstract: We report on a polarized Raman study on mechanically cleaved single-layer graphene films. Under a specific orientation of scattering measurement, the width and position of the G peak change with the incident polarization direction, while the integrated intensity of that is unaltered. This phenomenon is explained by a proposed mode in which the peak is contributed by a mixture of un-, compressive-, and tensile-strained G sub-modes. The compression and tension are both uniaxial and approximately perpendicular to each other. They are undesigned and located in either separated or overlapped sub-areas within the probed local region. Compared to the unstrained wavenumber of 1580 cm(-1), compression induces a blue shift while tension causes a red one. The sub-modes correlated with the light polarization through different relationships split the G peak into three sub-ones. We develop a method to quantitatively analyze the positions, widths, intensities, and polarization dependences of sub-peaks. This analysis quantitatively reveals local strain, which changes with the detected area of a graphene film. The method presented here can be extended to detect the strain distribution in the film and thus is a promising technology for graphene characterization.
authors.affiliation: Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan. chihiliu@mail.ncku.edu.tw.
authors.forename: Cheng-Wen
authors.initials: CW
authors.lastname: Huang
authors.forename: Ren-Jye
authors.initials: RJ
authors.lastname: Shiue
authors.forename: Hsiang-Chen
authors.initials: HC
authors.lastname: Chui
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Wang
authors.forename: Juen-Kai
authors.initials: JK
authors.lastname: Wang
authors.forename: Yonhua
authors.initials: Y
authors.lastname: Tzeng
authors.forename: Chih-Yi
authors.initials: CY
authors.lastname: Liu