Using negative chemical potential of graphene


#1

Could you please let me know how can I use negative vaues of chemical potential for graphene in Lumerical FDTD Solutions?

I have seen papers making use of negative chemical potential to indicate hole doping, Like int his one.

https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.7b04393


#2

Hi @vivek.shrestha

A chemical potential of zero means that the graphene is not doped. You can read more about the fermi levels in the link below:
http://www.nanoctr.cas.cn/gongjianru/keyanchengguo/201107/W020110811351729719665.pdf 2

Since the structure is symmetric, I think that results of n- and p-doping will be the same. In another words, you can use positive chemical potential for the same amount of n- and p-doping for optical simulations.

Graphene + MoS2 Heterostructure Modelling

Please let me know of your thoughts and share your references with me if you have any concerns.


#3

Thank you for your kind response. I am willing to use chemical potential of value zero ‘0’ for a mobility of 315 cm2/Vs. However this would give rise to scattering rate of infinity. How am I supposed to set the value of scattering rate in this case? I would appreciate your feedback.


#4

Hi @vivek.shrestha

I need to discuss your case with my colleague who is on vacation. I will get back to you early next week.

Thanks for your patience.


#5

Hello,

I would appreciate if you could let me know if you have any update about my problem i.e. How to set the scattering rate of graphene in case of chemical potential of zero ‘0’ for a given mobility value?

Thank you,
Vivek


#6

Hi @vivek.shrestha

Sorry for a delayed reply.

I assume you are referring to this equation in the KB page:

image
https://kb.lumerical.com/en/index.html?other_application_graphene_simulation_tips.html

Please note that this equation is valid only if the chemical potential is non-zero or graphene is doped. Authors makes different assumptions to obtain this ratio which will not be valid for a chemical potential of zero, for example see the paper linked below:
https://www.nature.com/articles/srep02105

For a chemical potential of zero, you can find the scattering rate from a reference and use the 2D graphene model to assign chemical potential and scattering rate values.

Hope this was helpful.