Wrote to Sujit S. Datta

 He is an outstanding student who made a lot of impressive work.
One of his previous work named "Surface Potentials and Layer Charge Distributions in Few-Layer Graphene Films" is an important reference for my KPM study.
When I found his website and blog, I am so excited because he also shared the idea and comments about scientific research just like me.
And I asked him some questions about the article I just mentioned, and I listed them as follows:
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(1) You mentioned that the surface potential of few layer graphene(FLGs) on SiO2 substrate is always positive, indicating hole doping in ambient.
But what about single layer graphene?
In our experiments, they sometimes exhibit higher potential than surrounding silica but sometimes lower than that. Could such variation be an evidence for doping tendency?
(2) The surface potential of FLGs increases with film thickness and  approach to a finite value is resulted from "interlayer screening".
Is that means each graphene layer can "feel" positive charges on the bottom layer which is strongly doped by holes from silica?
And will each layer redistribute the electron density to adapt the positive surface charges of the bottom layer?
If the bottom layer is doped by negative electrons, instead of holes. Would it be possible that the potential of FLGs may decrease with layer thickness, or it still increases with film thickness?
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Surprisingly, he replied me very fast !
In spite of some unanswered questions, I’m so grateful to him!