# What is an electron hole pair?

• I
• anaqavi
In summary, the density of electrons and holes are equal in an intrinsic semiconductor at equilibrium, as holes are simply lack of electrons that have escaped from atoms. However, in a p-doped semiconductor, the number of holes can be much larger than the number of electrons due to the process of doping, where we can add electrons or holes separately. Pure gallium and arsenic are not semiconductors, with gallium being a metal and arsenic being a semi-metal.
anaqavi
TL;DR Summary
Why are more electrons than holes in an n-type semiconductor?
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?

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

## What is an electron hole pair?

An electron hole pair is a phenomenon that occurs when an electron in a material is excited to a higher energy state, leaving behind an empty space called a "hole". This hole behaves like a positively charged particle and can move through the material, creating a flow of electric current.

## How is an electron hole pair created?

An electron hole pair can be created in a material through various processes, such as absorption of a photon, thermal excitation, or impact ionization. These processes result in the promotion of an electron from the valence band to the conduction band, leaving behind a hole in the valence band.

## What is the significance of electron hole pairs in semiconductors?

In semiconductors, the movement of electron hole pairs is responsible for the flow of electric current. By controlling the number and movement of these pairs, the conductivity of a semiconductor material can be manipulated, making it a crucial aspect of modern electronic devices.

## Can electron hole pairs be separated?

Yes, electron hole pairs can be separated through various methods, such as applying an external electric field or using a p-n junction. This separation allows for the creation of a potential difference, which is essential for the functioning of electronic devices.

## What happens to an electron hole pair when it recombines?

When an electron hole pair recombines, the electron falls back to its original energy state, and the hole is filled. This process releases energy in the form of a photon or heat. In electronic devices, this recombination can lead to a loss of efficiency, so measures are taken to minimize it.

• Atomic and Condensed Matter
Replies
2
Views
2K
• Atomic and Condensed Matter
Replies
2
Views
2K
• Atomic and Condensed Matter
Replies
5
Views
2K
• Quantum Physics
Replies
2
Views
1K
• Electromagnetism
Replies
1
Views
746
• Atomic and Condensed Matter
Replies
3
Views
3K
• Atomic and Condensed Matter
Replies
7
Views
2K
• Chemistry
Replies
8
Views
1K
• Atomic and Condensed Matter
Replies
4
Views
4K
• Atomic and Condensed Matter
Replies
2
Views
2K