What is the direction of flow of majority charge carriers in reverse biased pn junction?
In reverse bias condition, the positive terminal is connected to the n-type and the negative terminal is connected to the p-type. Hence, majority charge carriers are swept into terminals and minority charge carriers are repelled by the terminals.
What causes a very small current flow in a reverse biased PN junction?
When a diode is reversed bias, the width of the depletion region increases. This restricts the current carrier accumulation near the junction. Majority current carriers are primarily negated in the depletion region and hence the depletion region acts as an insulator. This current is called leakage current.
How does the reverse biased junction in a transistor work?
Here’s how it works: Current through the reverse biased junction in transistor. A transistor is a three terminal device. One terminal is called emitter, one collector and in between them is base. Now, during biasing the junction between emitter and base is made forward biased and the junction between collector and base is made reverse biased.
How is the base emitter biased in a transistor?
The base emitter junction is forward biased to allow current to be injected into the emitter. The transistor uses this small injected current and amplifies it in the current that flows from Collector to Emitter. The mechanisms for that are complicated and I won’t cover it.
How does reverse biasing affect the diffusion current?
You are reverse biasing the base-collector junction, which almost completely shuts off the diffusion current from base to collector, but the drift current from collector to base is proportional to the number of electrons near the edge of the depletion region on the base side. The emitter is injecting electrons into the base through diffusion.
How does a reverse biased diode work in reverse?
A PNP transistor works the same way but in reverse. From a first approximation, the depletion zone of a reverse-biased diode is simply an insulating region. But this doesn’t explain the collector junction of a transistor. We need to look at this insulation-effect in more detail.