Graphene films can be used as a transparent electrode. Currently O2 plasma etching was used to etch the graphene. Is there any way to remove some of the graphene area for the thickness measurement?
You can always mask the graphene sheet with photoresist or metal (normally Aluminium) and etch unmasked graphene in plasma. Then wash the mask away (with acetone or NMP for the resist / with KOH, or TMAH, or acid-based Al etch for Aluminium mask) and measure thickness of the remaining graphene. Keep in mind that the resist/PMMA mask will leave some residue after being dissolved, which can potentially distort your thickness measurement. Good luck.
You can always mask the graphene sheet with photoresist or metal (normally Aluminium) and etch unmasked graphene in plasma. Then wash the mask away (with acetone or NMP for the resist / with KOH, or TMAH, or acid-based Al etch for Aluminium mask) and measure thickness of the remaining graphene. Keep in mind that the resist/PMMA mask will leave some residue after being dissolved, which can potentially distort your thickness measurement. Good luck.
Thanks Andrey for the input, however the graphene sheet was coated on the glass.Is the proposed method work for this samples or u have others advice..
Rafidah, can you please be more specific about your system? Is it a graphene sheet transfered/grown on glass substrate? Is graphene covered by something else?
Generally, the method I described above is rather universal and can be applied to variety of different substrates (glass, silicon, quartz, thermal silicon dioxide, silicon nitride, GaAs, metals). In case of insulating substrates one can experience poor resist/PMMA adhesion. This problem can easily be resolved by spinning HMDS Primer prior to the resist (refer to the Primer data sheet for more detailed process description).
The graphene was grown on the copper foil and then transferred to glass substrate. The graphene/ glass substrate used as a transperent electrode for organic solar cell. Thanks.
Rafideh, I am not quite sure why you are trying to measure the thickness of transferred CVD grown graphene (presumably monolayer), however, you may also try using Raman spectroscopy to estimate number of layers. This method works best for monolayer, however, it can be also used for few layer graphene. Basically you need to look at FWHM of 2D band in the Raman spectrum of your sample. Details can be found in the work done by Hao et al:
Y. Hao, Y. Wang, L. Wang, Z. Ni, Z. Wang, R. Wang, C. K. Koo, Z. Shen, and J. T. L. Thong, “Probing layer number and stacking order of few-layer graphene by Raman spectroscopy.,” Small (Weinheim an der Bergstrasse, Germany), vol. 6, no. 2, pp. 195–200, Jan. 2010.
If your sample is monolayer, then the thickness is around 3.5 A. Hope this helps.
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