Understand PN Junction Diode: Diffusion & Electrons

In summary, the amount of doping and the applied forward bias voltage determine whether all or some of the dominant charge carriers in the P and N junctions of a diode recombine and become neutral. Doping concentrations are small compared to the total number of atoms, so there will always be free electrons left. The atoms become ions, not the other way around, and these ions form the source of the electric fields and voltage difference. Holes and electrons recombine with each other, but the ions remain unchanged.
  • #1
M.Kalai vanan
32
0
If p-type semiconductor and n-type semiconductor of a diode are equally doped, and if the diode is forward biased, then holes will move toward the n-type semiconductor and electrons will move toward the p-type semiconductor and they will diffuse with each other and the ions become neutral atoms since the hole and electron have disappeared. Then will there be any electron that will go to the positive terminal of the battery if all of them have diffused with each other? I can't understand, please help me!
 
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  • #2
The amount of doping in the P and N junctions determines whether ALL or SOME of them recombine and become neutral. Also, the width of the depletion region gets thinner as forward bias voltage is applied across the diode, and this process too determines whether all or some of the dominant charge carriers in the semiconductor junction actually recombine to neutrality.
 
  • #3
Doping concentrations are tiny compared to the total number of atoms - there are always electrons left.

and the ions become neutral atoms since the hole and electron have disappeared.
It is the other way round, the atoms become ions. Holes are not ions - they are spots where an additional electron can be bound. And free electrons come from atoms where one electron is not bound, so it will easily form an ion.
Those ions are then the source for the electric fields and therefore the voltage difference, by the way.
 
  • #4
then it becomes neutral
 

1. What is a PN junction diode?

A PN junction diode is a semiconductor device that allows current to flow in only one direction. It is formed by combining a p-type semiconductor (which has an excess of positively charged holes) and an n-type semiconductor (which has an excess of negatively charged electrons).

2. How does a PN junction diode work?

In a PN junction diode, the p-type and n-type semiconductors are brought into contact, creating a depletion region where the majority carriers (electrons in the n-type and holes in the p-type) are depleted. When a forward bias voltage is applied, the depletion region becomes thinner and allows current to flow through the diode.

3. What is diffusion in a PN junction diode?

Diffusion is the movement of charge carriers (electrons and holes) from an area of high concentration to an area of low concentration. In a PN junction diode, diffusion occurs when the majority carriers move from one side of the junction to the other, creating a current flow.

4. How do electrons behave in a PN junction diode?

Electrons in a PN junction diode behave differently depending on the direction of the applied voltage. In a forward bias, electrons in the n-type semiconductor are pushed towards the depletion region and combine with holes in the p-type, creating current flow. In a reverse bias, electrons are repelled from the depletion region and no current flows.

5. What are the applications of PN junction diodes?

PN junction diodes have a variety of applications, including rectification (converting AC to DC), voltage regulation, and signal detection in electronic circuits. They are also commonly used in solar cells, LED lights, and photodiodes for detecting light.

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