Characterization of polycrystalline graphene based CVD by laser polarization Raman

Graphene has excellent physical and chemical properties, and has become a research hotspot in the fields of MEMS devices, photoelectric detection materials, flexible display screens, new energy batteries and composite materials. At present, the preparation of large area graphene mainly depends on chemical vapor deposition (CVD), but the crystal quality of graphene growth directly affects the electrochemical characteristics and practical applications, so a fast and accurate characterization method is needed. Raman spectra of graphene grown by CVD were measured by backscattering polarized laser scattering device. Angular resolved polarization Raman spectra of graphene on 300 nm SiO₂/Si substrates were analyzed. It was found that the polarization characteristics of graphene grown in single layer were consistent with those of mechanically stripped graphene. The polarization response of G peak was more distinct with the increase of the number of layers, showing obvious elliptical characteristics. In graphene samples with different layers, the defects in the samples showed obvious D peaks and polarization responses due to the increase of layers. The polarization states of the 2D peaks were not significantly different in different samples and were not affected by the number of layers. Polarization Raman measurements show that the defects and polycrystalline properties of CVD growth are positively correlated with the number of graphene layers.