PhysicsChapter 9: Electronics
The P-N Junction
Introduction
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.
Definition
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.
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Sticky Notes · Quick Revision
P-N JUNCTION
- P | depletion | N
BIAS
- Forward → conducts
- Reverse → blocks
60-second revision
- P + N → junction.
- Junction → depletion region.
- Forward → barrier reduced.
- Reverse → barrier increased.
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