Revealing anisotropic strain in exfoliated graphene by polarized Raman spectroscopy

• Published in: Nanoscale Vol. 5; no. 20; pp. 9626 - 9632
• Main Authors: Huang, Cheng-Wen, Shiue, Ren-Jye, Chui, Hsiang-Chen, Wang, Wei-Hua, Wang, Juen-Kai, Tzeng, Yonhua, Liu, Chih-Yi
• Format: Journal Article
• Language: English
• Published: England 21.10.2013
• Subjects: Anisotropy; Blue shift; Graphene; Nanostructure; Polarization; Strain; Strain distribution; Wavenumber
• DOI: 10.1039/c3nr00123g
• ISSN: 2040-3364

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.