# Characterizing graphene

> Six measurements tell you what a graphene flake is. Optical contrast on SiO₂/Si finds it, AFM and the Raman spectrum count its layers, the Raman D band gives the distance between its defects, electron diffraction tells one layer from two, and a field-effect device gives its carrier density and mobility.

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- Open in the LabCanvas editor (LabCanvas account): https://www.labcanvas.com/editor.html?template=graphene-characterization
- Updated: 2026-10-14
- Category: Graphene research
- Method: Characterization
- Starting materials: Exfoliated or CVD graphene on SiO₂/Si (suspended over holes for TEM)
- Product: Layer number, defect density, crystal structure, carrier density and mobility
- Key result: Images, spectra and curves computed by LabCanvas from the cited measurements and models; the micrograph’s colours from thin-film optics; the transfer curve’s residual carrier density and contact resistance are illustrative
- Figure: 1920 × 1080 px, 46 editable layers (7 generated objects with settings)

## Steps

1. **Optical contrast**: On oxidised silicon, thin-film interference makes a single layer visible; the colours here are computed for graphene with n = 2.6 − 1.3i and 0.34 nm per layer (Blake et al. 2007)
2. **AFM height**: Each layer adds graphite’s interlayer spacing, 0.335 nm; tapping-mode AFM can add as much as 1 nm to the measured height of thin flakes (Nemes-Incze et al. 2008)
3. **Raman spectrum**: At 532 nm a monolayer shows the G band at 1582 cm⁻¹ and one sharp 2D band at 2675 cm⁻¹, about 28 cm⁻¹ wide and 3.6 times as intense; the 2D band changes shape, width and position with the number of layers (Ferrari et al. 2006; Qiu et al. 2016)
4. **Defect density**: I(D)/I(G) against the mean distance between defects, L_D, rises to a maximum near 3 nm and depends on the laser; for L_D ≥ 10 nm, L_D² ≈ 4.3 × 10³ / (E_L⁴ · I(D)/I(G)), with L_D in nm and the laser energy E_L in eV (Cançado et al. 2011)
5. **Electron diffraction**: Six-fold spots from the periodicities of 2.13 and 1.23 Å (Meyer et al. 2007); a monolayer’s inner {101̅0} spots are brighter than its outer {112̅0} ones, while in thicker stacks the inner ones are weaker (Hernandez et al. 2008)
6. **Field effect**: The resistance peaks at the Dirac point; on 300 nm SiO₂ each volt on the gate adds 7.2 × 10¹⁰ carriers per cm², and the first devices reached about 10,000 cm²/V·s at room temperature (Novoselov et al. 2004); curve from the model of Kim et al. (2009)

## Strengths

- Raman identifies the number of layers without damage and at high throughput (Ferrari et al. 2006)
- The same Raman spectrum also measures the distance between defects (Cançado et al. 2011)
- With monochromatic light graphene can be seen on any SiO₂ thickness; 300 nm and especially about 100 nm suit the eye best (Blake et al. 2007)

## Limitations

- AFM heights of thin flakes can be off by as much as 1 nm (Nemes-Incze et al. 2008)
- Visibility depends strongly on the SiO₂ thickness and the wavelength (Blake et al. 2007)
- Electron diffraction needs sheets suspended across holes (Meyer et al. 2007)

## Uses

- Quality control of exfoliated, CVD and solution-processed graphene
- Choosing flakes for devices

## References

1. Ferrari et al., “Raman spectrum of graphene and graphene layers”, Phys. Rev. Lett. 2006. https://doi.org/10.1103/PhysRevLett.97.187401 (primary)
2. Blake et al., “Making graphene visible”, Appl. Phys. Lett. 2007. https://doi.org/10.1063/1.2768624 (primary)
3. Cançado et al., “Quantifying defects in graphene via Raman spectroscopy at different excitation energies”, Nano Lett. 2011. https://doi.org/10.1021/nl201432g (primary)
4. Meyer et al., “The structure of suspended graphene sheets”, Nature 2007. https://doi.org/10.1038/nature05545 (primary)
5. Novoselov et al., “Electric field effect in atomically thin carbon films”, Science 2004. https://doi.org/10.1126/science.1102896 (primary)
6. Nemes-Incze et al., “Anomalies in thickness measurements of graphene and few layer graphite crystals by tapping mode atomic force microscopy”, Carbon 2008. https://doi.org/10.1016/j.carbon.2008.06.022 (further reading)
7. Qiu et al., “Raman and conductivity analysis of graphene for biomedical applications”, Materials 2016. https://doi.org/10.3390/ma9110897 (further reading)
8. Hernandez et al., “High-yield production of graphene by liquid-phase exfoliation of graphite”, Nat. Nanotechnol. 2008. https://doi.org/10.1038/nnano.2008.215 (further reading)
9. Kim et al., “Realization of a high mobility dual-gated graphene field-effect transistor with Al2O3 dielectric”, Appl. Phys. Lett. 2009. https://doi.org/10.1063/1.3077021 (further reading)
10. Nair et al., “Fine structure constant defines visual transparency of graphene”, Science 2008. https://doi.org/10.1126/science.1156965 (further reading)

Credit: Computed by LabCanvas after Ferrari et al., PRL 2006 (doi:10.1103/PhysRevLett.97.187401), Cançado et al., Nano Lett. 2011, Blake et al., APL 2007, Meyer et al., Nature 2007, Novoselov et al., Science 2004, and the papers in the details.

## Questions

**What does the “Characterizing graphene” template show?** Six measurements tell you what a graphene flake is. Optical contrast on SiO₂/Si finds it, AFM and the Raman spectrum count its layers, the Raman D band gives the distance between its defects, electron diffraction tells one layer from two, and a field-effect device gives its carrier density and mobility.

**What are the steps shown in “Characterizing graphene”?** 1. Optical contrast: On oxidised silicon, thin-film interference makes a single layer visible; the colours here are computed for graphene with n = 2.6 − 1.3i and 0.34 nm per layer (Blake et al. 2007). 2. AFM height: Each layer adds graphite’s interlayer spacing, 0.335 nm; tapping-mode AFM can add as much as 1 nm to the measured height of thin flakes (Nemes-Incze et al. 2008). 3. Raman spectrum: At 532 nm a monolayer shows the G band at 1582 cm⁻¹ and one sharp 2D band at 2675 cm⁻¹, about 28 cm⁻¹ wide and 3.6 times as intense; the 2D band changes shape, width and position with the number of layers (Ferrari et al. 2006; Qiu et al. 2016). 4. Defect density: I(D)/I(G) against the mean distance between defects, L_D, rises to a maximum near 3 nm and depends on the laser; for L_D ≥ 10 nm, L_D² ≈ 4.3 × 10³ / (E_L⁴ · I(D)/I(G)), with L_D in nm and the laser energy E_L in eV (Cançado et al. 2011). 5. Electron diffraction: Six-fold spots from the periodicities of 2.13 and 1.23 Å (Meyer et al. 2007); a monolayer’s inner {101̅0} spots are brighter than its outer {112̅0} ones, while in thicker stacks the inner ones are weaker (Hernandez et al. 2008). 6. Field effect: The resistance peaks at the Dirac point; on 300 nm SiO₂ each volt on the gate adds 7.2 × 10¹⁰ carriers per cm², and the first devices reached about 10,000 cm²/V·s at room temperature (Novoselov et al. 2004); curve from the model of Kim et al. (2009).

**What are the starting materials and the product?** Starting materials: Exfoliated or CVD graphene on SiO₂/Si (suspended over holes for TEM). Product: Layer number, defect density, crystal structure, carrier density and mobility.

**Which papers is “Characterizing graphene” based on?** Ferrari et al., “Raman spectrum of graphene and graphene layers”, Phys. Rev. Lett. 2006 (doi:10.1103/PhysRevLett.97.187401); Blake et al., “Making graphene visible”, Appl. Phys. Lett. 2007 (doi:10.1063/1.2768624); Cançado et al., “Quantifying defects in graphene via Raman spectroscopy at different excitation energies”, Nano Lett. 2011 (doi:10.1021/nl201432g); Meyer et al., “The structure of suspended graphene sheets”, Nature 2007 (doi:10.1038/nature05545); Novoselov et al., “Electric field effect in atomically thin carbon films”, Science 2004 (doi:10.1126/science.1102896); Nemes-Incze et al., “Anomalies in thickness measurements of graphene and few layer graphite crystals by tapping mode atomic force microscopy”, Carbon 2008 (doi:10.1016/j.carbon.2008.06.022); Qiu et al., “Raman and conductivity analysis of graphene for biomedical applications”, Materials 2016 (doi:10.3390/ma9110897); Hernandez et al., “High-yield production of graphene by liquid-phase exfoliation of graphite”, Nat. Nanotechnol. 2008 (doi:10.1038/nnano.2008.215); Kim et al., “Realization of a high mobility dual-gated graphene field-effect transistor with Al2O3 dielectric”, Appl. Phys. Lett. 2009 (doi:10.1063/1.3077021); Nair et al., “Fine structure constant defines visual transparency of graphene”, Science 2008 (doi:10.1126/science.1156965).

**Can I edit the “Characterizing graphene” template?** Yes. Open it in the LabCanvas editor: all 46 layers are editable, including 7 generated objects (structures, plots, equipment) with their own settings. Change the text, colours and layout, then export PNG, TIFF, SVG or PDF.

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