I have made CVD graphene samples and now the goal is to calculate its Carrier Concentration and Dirac point. How can I do this? What measurements do I need to provide to calculate these quantities?
Thank you for your attention and time!
Dear Oleksandr,
First of all, you have to have a full device with the source, and drain and back gate electrodes i.e (FET device ) where graphene here is the channel. then by applying a low bias voltage (Vsd) let's say (0.1 V) and different Vg, you can exam the electrical properties of graphene to check if it is doped and not. If you calculate the resistance as a function of Vg, you can now observe where the highest peak of resistance is. If this point lies above 0 Vg, it means graphene is undoped and Dirac point lies also above 0 Vg. Otherwise, it shifts to either positive or negative Vg corresponding to Hole or Electron doping and Dirac point now is corresponding to a Vg value where the highest resistance is shifted. Now you need to use a formula found in the paper below to calculate the Carrier Concentration of electrons and holes
Solid State Communications 175-176 (2013) 18–34. The electrons/Holes mobility can be extracted from the slope of doping dependence of the device resistance near Dirac Point.
Hope that helps.
Dear Oleksandr,
First of all, you have to have a full device with the source, and drain and back gate electrodes i.e (FET device ) where graphene here is the channel. then by applying a low bias voltage (Vsd) let's say (0.1 V) and different Vg, you can exam the electrical properties of graphene to check if it is doped and not. If you calculate the resistance as a function of Vg, you can now observe where the highest peak of resistance is. If this point lies above 0 Vg, it means graphene is undoped and Dirac point lies also above 0 Vg. Otherwise, it shifts to either positive or negative Vg corresponding to Hole or Electron doping and Dirac point now is corresponding to a Vg value where the highest resistance is shifted. Now you need to use a formula found in the paper below to calculate the Carrier Concentration of electrons and holes
Solid State Communications 175-176 (2013) 18–34. The electrons/Holes mobility can be extracted from the slope of doping dependence of the device resistance near Dirac Point.
Hope that helps.
Dear Omar Dawood,
Thank you for such a good answer!
I hope that I will make all right.
Dear Oleksandr,
A FET device is suitable for extracting mobility and carrier concentration.
Another option is to measure the Quantum Hall effect. you can read the following paper
http://iopscience.iop.org/article/10.1088/1742-6596/456/1/012006/pdf
Since such measurements and instrumentation require experience, ask people in your lab that can help you realizing them.
Good luck!
Dear Stefanos Chaitoglou,
Thank you for your answer! I hope it will help me!
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