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The P-N Junction
A P-N junction forms a depletion region with a potential barrier. Forward bias reduces the barrier; reverse bias increases it — the basis of diode operation.
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The P-N Junction
When P-type and N-type materials meet, a special boundary forms.
This boundary helps a diode control which direction current can easily flow.
Recommended for Class 10
The P-N Junction
A P-N junction is formed when P-type and N-type semiconductor regions meet.
Near the junction, electrons from the N-side and holes from the P-side can move across the boundary and recombine.
This produces a region near the boundary with very few mobile charge carriers.
This region is called the depletion region.
The fixed charged ions left in this region create an internal electric field and a potential barrier that opposes further carrier diffusion.
Forward Bias
Forward bias reduces the effective barrier.
Current can then flow much more easily.
Reverse Bias
Reverse bias increases the effective barrier and widens the depletion region.
Only a very small reverse current normally flows before breakdown conditions.
Importance
The P-N junction is the basic operating structure of a semiconductor diode.
The P-N Junction — Advanced
Carrier diffusion and recombination expose ionized dopants near the junction, creating a space-charge region and built-in electric field. Applied bias changes the junction barrier and depletion width.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
P + N → junction.
Junction → depletion region.
Forward → barrier reduced.
Reverse → barrier increased.
- Definition
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Practice
PQ
Q1. Define P-N junction.
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Q2. Depletion region.
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Q3. Forward bias.
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Q4. Reverse bias.
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Q5. Why junction is important.
Exam Practice
EQ
Q1. Explain formation of P-N junction.
EQ
Q2. What is depletion region?
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Q3. Explain potential barrier.
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Q4. Describe forward bias.
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Q5. Describe reverse bias.
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.