Please explain me - width of depletion layer varies

In summary, the width of the depletion layer in a junction varies with different factors. When the doping content decreases, the width increases due to neutralization occurring sooner. However, in the case of thyristor, when the voltage is increased in forward blocking state, the width of the reversed biased j2 junction decreases. This is due to the voltage being relative to other junctions and locally less reverse biased.
  • #1
abhishek91
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please explain me -- width of depletion layer varies

hey guys,
i need to know how does width of depletion layer varies with various factors and i have mentioned all my queries below
1.first of all i want to know how does width of depletion layer increases with decrease in doping content??as per my knowledge when p and n regions r combined to form a junction electrons from n region and holes from p region move to p and n regions respectively leaving behind immobile charges and from this we can conclude that as the doping content increases width should decrease but opposite of this actually happens.why and how?
2.when we increase the potential drop in case of reverse bias, width of depletion layer increases but in case of thyristor when it is in forward blocking state and we increase the voltage the width of j2 junction which is reversed biased decreases that's what given in md singh and khanchandani. how does all this happen..please someone explain this ...
thanks
 
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  • #2


Semiconductors 101:

http://en.wikipedia.org/wiki/Depletion_region

1. Increasing doping causes neutralization to occur "sooner" in distance ergo smaller width, and vice versa.

2. The voltage is relative to other junctions - locally it is less reverse biased.
 

1. What is a depletion layer?

A depletion layer is a region in a semiconductor material that lacks free charge carriers due to the presence of a built-in electric field. This can occur in a p-n junction, where the region near the junction becomes depleted of electrons in the n-type material and holes in the p-type material.

2. Why does the width of the depletion layer vary?

The width of the depletion layer varies depending on the type of semiconductor material used, the doping concentration, and the applied voltage. It can also be affected by temperature changes and the presence of impurities in the material.

3. How does the width of the depletion layer affect the behavior of a semiconductor device?

The width of the depletion layer determines the size of the barrier that must be overcome for current to flow through a semiconductor device. A wider depletion layer means a larger barrier and therefore a higher resistance to current flow.

4. Can the width of the depletion layer be controlled?

Yes, the width of the depletion layer can be controlled by changing the doping concentrations or by applying an external voltage. This is an important aspect of designing and controlling the behavior of semiconductor devices.

5. What is the significance of the width of the depletion layer in solar cells?

In solar cells, the width of the depletion layer is crucial for efficient conversion of light into electricity. A wider depletion layer allows for a larger absorption of photons, increasing the efficiency of the solar cell. However, if the depletion layer is too wide, it can lead to a decrease in current flow and reduce the overall efficiency of the solar cell.

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