What is an electron hole pair?

  • I
  • Thread starter anaqavi
  • Start date
  • #1
6
0

Summary:

Why are more electrons than holes in an n-type semiconductor?

Main Question or Discussion Point

Hi,

These questions may seem basic, yet, I do not have an answer for that.

The density of electrons and the density of holes in an intrinsic semiconductor are equal at equilibrium. From this, it seems that holes are simply lack of electrons that are given enough (thermal) energy to escape from a particular atom. Therefore, it is evident that the number of electrons and holes will be equal because for each electron that escapes from an atom an empty place -a hole- will be created.

However, when we consider a p-doped semiconductor, the number of holes will be much larger than the number of electrons. If a hole is simply lack of an electron, as in the previous case we should be able to conclude that the number of electrons and holes are equal. How to solve this contradictory reasoning?

Another question: Are pure Arsenide and pure Gallium assumed intrinsic?
 

Answers and Replies

  • #2
phyzguy
Science Advisor
4,370
1,346
In a pure semiconductor like silicon, you are right in that the number of electrons and holes will be equal. However, by doping the semiconductor, we can add electrons without adding holes, or holes without adding electrons. For example, in an N-type semconductor in the case of silicon, we dope the silicon by adding a group 5 element, which has 1 more valence electron. In this case the charge of the extra electron is compensated by the added charge in the nucleus of the group 5 doping element, not by an extra hole.

Pure gallium and pure arsenic are not semiconductors. Gallium is a metal, and arsenic is a semi-metal
 

Related Threads for: What is an electron hole pair?

  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
2
Views
5K
Replies
5
Views
1K
Replies
0
Views
2K
  • Last Post
Replies
2
Views
2K
Replies
3
Views
2K
Replies
20
Views
6K
Replies
16
Views
4K
Top