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Probing substrate influence on graphene by analyzing Raman lineshapes.

Huang CH, Lin HY, Huang CW, Liu YM, Shih FY, Wang WH, Chui HC - Nanoscale Res Lett (2014)

Bottom Line: Distinguishing the substrate influences or the doping effects of charged impurities on graphene can be realized by optically probing the graphene surfaces, included the suspended and supported graphene.For the Gaussian part, the suspended graphene exhibits much greater Gaussian bandwidths than those of the supported graphene.It reveals that the doping effect on supported graphene is stronger than that of suspended graphene.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan. hcchui@mail.ncku.edu.tw.

ABSTRACT
We provide a new approach to identify the substrate influence on graphene surface. Distinguishing the substrate influences or the doping effects of charged impurities on graphene can be realized by optically probing the graphene surfaces, included the suspended and supported graphene. In this work, the line scan of Raman spectroscopy was performed across the graphene surface on the ordered square hole. Then, the bandwidths of G-band and 2D-band were fitted into the Voigt profile, a convolution of Gaussian and Lorentzian profiles. The bandwidths of Lorentzian parts were kept as constant whether it is the suspended and supported graphene. For the Gaussian part, the suspended graphene exhibits much greater Gaussian bandwidths than those of the supported graphene. It reveals that the doping effect on supported graphene is stronger than that of suspended graphene. Compared with the previous studies, we also used the peak positions of G bands, and I2D/IG ratios to confirm that our method really works. For the suspended graphene, the peak positions of G band are downshifted with respect to supported graphene, and the I2D/IG ratios of suspended graphene are larger than those of supported graphene. With data fitting into Voigt profile, one can find out the information behind the lineshapes.

No MeSH data available.


The Raman spectrum of graphene and the related fitting parameter of the Raman spectra. (a) The Raman spectrum (black line) of graphene, the Lorentzian-fitted profile (blue line), and the Voigt-fitted profile (red line). (b) The related fitting parameter of the Raman spectra.
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Figure 3: The Raman spectrum of graphene and the related fitting parameter of the Raman spectra. (a) The Raman spectrum (black line) of graphene, the Lorentzian-fitted profile (blue line), and the Voigt-fitted profile (red line). (b) The related fitting parameter of the Raman spectra.

Mentions: where the Gaussian profile and Lorentzian profile are expressed as G(ω, γ) and L(ω, Γ), and γ and Γ are their bandwidths. In Figure 3a, the typical Raman spectrum (black line) of graphene was shown with the Lorentzian-fitted profile (blue line) and the Voigt-fitted profile (red line). The related fitting parameter of the Raman spectrum was showed in Figure 3b.


Probing substrate influence on graphene by analyzing Raman lineshapes.

Huang CH, Lin HY, Huang CW, Liu YM, Shih FY, Wang WH, Chui HC - Nanoscale Res Lett (2014)

The Raman spectrum of graphene and the related fitting parameter of the Raman spectra. (a) The Raman spectrum (black line) of graphene, the Lorentzian-fitted profile (blue line), and the Voigt-fitted profile (red line). (b) The related fitting parameter of the Raman spectra.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3924919&req=5

Figure 3: The Raman spectrum of graphene and the related fitting parameter of the Raman spectra. (a) The Raman spectrum (black line) of graphene, the Lorentzian-fitted profile (blue line), and the Voigt-fitted profile (red line). (b) The related fitting parameter of the Raman spectra.
Mentions: where the Gaussian profile and Lorentzian profile are expressed as G(ω, γ) and L(ω, Γ), and γ and Γ are their bandwidths. In Figure 3a, the typical Raman spectrum (black line) of graphene was shown with the Lorentzian-fitted profile (blue line) and the Voigt-fitted profile (red line). The related fitting parameter of the Raman spectrum was showed in Figure 3b.

Bottom Line: Distinguishing the substrate influences or the doping effects of charged impurities on graphene can be realized by optically probing the graphene surfaces, included the suspended and supported graphene.For the Gaussian part, the suspended graphene exhibits much greater Gaussian bandwidths than those of the supported graphene.It reveals that the doping effect on supported graphene is stronger than that of suspended graphene.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan. hcchui@mail.ncku.edu.tw.

ABSTRACT
We provide a new approach to identify the substrate influence on graphene surface. Distinguishing the substrate influences or the doping effects of charged impurities on graphene can be realized by optically probing the graphene surfaces, included the suspended and supported graphene. In this work, the line scan of Raman spectroscopy was performed across the graphene surface on the ordered square hole. Then, the bandwidths of G-band and 2D-band were fitted into the Voigt profile, a convolution of Gaussian and Lorentzian profiles. The bandwidths of Lorentzian parts were kept as constant whether it is the suspended and supported graphene. For the Gaussian part, the suspended graphene exhibits much greater Gaussian bandwidths than those of the supported graphene. It reveals that the doping effect on supported graphene is stronger than that of suspended graphene. Compared with the previous studies, we also used the peak positions of G bands, and I2D/IG ratios to confirm that our method really works. For the suspended graphene, the peak positions of G band are downshifted with respect to supported graphene, and the I2D/IG ratios of suspended graphene are larger than those of supported graphene. With data fitting into Voigt profile, one can find out the information behind the lineshapes.

No MeSH data available.