The p-n Junction and the Depletion Region
Joining p-type and n-type materials
Forming a junction
A p-n junction is created when p-type and n-type semiconductor regions are joined. At the boundary, electrons and holes diffuse into each other and recombine, leaving behind charged ions.
Depletion region
The region near the junction that has very few mobile charge carriers is called the depletion region. It forms an internal electric field that affects current flow.
A built-in barrier
The depletion region acts like a barrier that makes current flow easier in one direction than the other.
Forward and reverse bias
When an external voltage reduces the barrier, the junction is forward biased and current flows easily. When the voltage increases the barrier, the junction is reverse biased and current is greatly reduced.
What is the depletion region?
The depletion region is depleted of mobile carriers near the junction.
Correct answer: A region with very few mobile charge carriers
What happens to the barrier in forward bias?
Forward bias lowers the barrier and allows current to flow more easily.
Correct answer: it is reduced
Why does a p-n junction matter in electronics?
The p-n junction is the basis of diode action.
Correct answer: It creates one-way current behavior
What happens at a p-n junction
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1
Step 1: Bring p-type and n-type regions together.
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2
Step 2: Electrons and holes diffuse across the boundary.
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3
Step 3: Recombination leaves fixed ions behind.
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Step 4: A depletion region forms.
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Step 5: The built-in field influences current flow.