Determining the type of semiconductor

[abhishek77492652]

Hello sir,
How can we determine whether the semiconductor  (let's say black phosphorus) is 'p' or 'n' type?
(In the tutorial for black phosphorus it is mentioned that it is p-type)

[Anders Blom]

A semiconductor is neither p-type or n-type until you dope it...

[davgumo]

Just add to Dr. Blom's response, I believe that completely intrinsic semiconductors are very difficult to fabricate. For example, MoS2 is synthesized with a high level of vacancies which makes it n-type. I assume a similar thing happens with phosphorene.

David

[Anders Blom]

Yes but then you also have to simulate it with the vacancies included, and then you already have introduced a form of doping, as I mentioned.

[Petr Khomyakov]

How can we determine whether the semiconductor  (let's say black phosphorus) is 'p' or 'n' type?
(In the tutorial for black phosphorus it is mentioned that it is p-type)

You may consult some textbooks on Solid State Physics, e.g., by Aschcroft & Mermin or any other. In the p(n)-type doped semiconductor, the Fermi level is shifted towards the valence (conduction) band from the middle of the gap. For highly-doped, degenerate semiconductors, the Fermi level may even be in the valence (conduction) band.