Hi everybody,
I saw in some articles, it is used parameter Vg (gate voltage) to change the fermi energy of graphene, But my question is how gate voltage is applied in monolayer graphene? In the other words, is it applied along the plane of garphene sheet or perpendicular to the graphene (along the thickness)?
Thank you
It depends on what you are trying to do. If you are trying to make a transistor it would be along the plane of the sheet. If you are trying to take AFM measurements etc. (which I am not sure how they would be usefull) it would be on the surface (perpedicular). So, it depends on the setting.
Vg is gate voltage, so you would have one electrode on top of graphene with a dielectric layer between them, and one electrode at the bottom of the transistor (below the substrate). But this also changes if it is a back-gated transistor, so again it depends.
Thank you dear Eleni,
Why the electrode is used with a dielectric spacer?
In a transistor, you need a dielectric between your semiconductor (graphene so to speak) and the metal so that a channel is formed between the drain and the source. Otherwise the carriers escape throught the gate, and this is not the operation that you want to achieve in a transistor.
However, I think that device physics are not that much related to what you are looking at.
I am not entirely sure, however I am currently doing research on electron transport and tunneling in Graphene (PDF attached). Please let me know if any of the techniques in my research could be of use to you.
Best Regards,
Dr Mark B Doost
Hi Arezou,
A gate voltage can be applied to a top-gate electrode as described by Eleni, or to the substrate which acts as a back-gate when the graphene is positioned on an SiO2/Si substrate (or similar). In the latter case the voltage is applied between the Si substrate and the drain (or source) but because the insulator layer is typically quite thick in this case (i.e. ~300 nm) the gate voltages are also relatively high (~10's of Volt).
Regards
Rob Elliman
I really thanks everybody for their responses.
Also, Dear Mark B. Doost your techniques are very good and interesting but unfortunately they are not now in my use.
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