How Does Conductivity Increase in N-Type Semiconductors?

[gracy]

How conductivity increases in n type semiconductor as ni^2 (formula nh multiplied by ne=ni^2 where nh=number of holes per unit volume and ne=number of free electrons per unit volume and ni=number of intrinsic charge carrier per unit volume remain constant?What is the use of increased number of electrons in conduction band as increasing number of electrons in conduction band decreases number of holes which were also capable of producing current i.e increasing conductivity.So overall no net increase in conductivity because as we are increasing number of electrons in conduction band at the same time we are loosing number of holes.please explain this.

 

[mfb]

Holes in the conduction band cannot produce a current. There is nothing that could move. Same with electrons in the valence band - they are bound and cannot move.

 

[gracy]

Holes in the conduction band cannot produce a current. There is nothing that could move. Same with electrons in the valence band - they are bound and cannot move.

so why there is a concept called ' HOLE CURRENT'?

 

[Vagn]

so why there is a concept called ' HOLE CURRENT'?

The hole current is caused by holes in the valence band (this corresponds to electrons in the conduction band).

 

[pmacias]

I can explain the concept of N-type semiconductors and how the conductivity increases in this type of semiconductor. N-type semiconductors are made up of materials such as silicon or germanium that have impurities added to them. These impurities, also known as dopants, introduce additional electrons into the material, creating an excess of free electrons.

The formula nh multiplied by ne=ni^2, where nh is the number of holes per unit volume and ne is the number of free electrons per unit volume, represents the equilibrium between the number of holes and free electrons in an N-type semiconductor. This equilibrium is maintained by the number of intrinsic charge carriers, ni, which remains constant.

Now, to address the question of how the conductivity increases in an N-type semiconductor, we need to understand the role of the excess free electrons. These free electrons are able to move more easily through the material, making it easier for electricity to flow. This is why N-type semiconductors are known as good conductors.

As the number of free electrons increases, the number of holes decreases. This is because the free electrons fill the holes, leaving fewer holes available for current flow. This decrease in the number of holes may seem counterintuitive, but it actually contributes to the increase in conductivity. This is because the holes, being positively charged, can hinder the movement of free electrons. So, by decreasing the number of holes, the free electrons can move more freely, resulting in a higher conductivity.

In summary, the increased number of electrons in the conduction band of an N-type semiconductor does not directly contribute to an increase in conductivity. However, by decreasing the number of holes, it allows for easier movement of the free electrons, resulting in a higher conductivity. This is why N-type semiconductors are commonly used in electronic devices where high conductivity is desired.