In a PN junction diode, what happens when it is forward biased? (2019)

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Question: In a PN junction diode, what happens when it is forward biased? (2019)

Options:

Correct Answer: Depletion region narrows

Exam Year: 2019

Solution:

When a PN junction diode is forward biased, the depletion region narrows, allowing current to flow.

In a PN junction diode, what happens when it is forward biased? (2019)

In a PN junction diode, what happens when it is forward biased? (2019)

Step 1: Understand what a PN junction diode is. It is made of two types of semiconductor materials: P-type (positive) and N-type (negative).
Step 2: Identify what forward biasing means. Forward biasing occurs when the positive side of the power supply is connected to the P-type material and the negative side is connected to the N-type material.
Step 3: Recognize that in forward bias, the electric field created by the power supply reduces the barrier that prevents current flow.
Step 4: Observe that as the barrier is reduced, the depletion region (the area where no charge carriers exist) becomes narrower.
Step 5: Conclude that with the depletion region narrowed, charge carriers (electrons and holes) can move across the junction, allowing current to flow through the diode.

Forward Biasing – In a PN junction diode, forward biasing occurs when the positive terminal of the voltage source is connected to the p-type material and the negative terminal to the n-type material, reducing the width of the depletion region and allowing current to flow.
Depletion Region – The depletion region is the area around the PN junction where mobile charge carriers are depleted, and its width is affected by the applied voltage.
Current Flow – When the diode is forward biased, the applied voltage overcomes the potential barrier, allowing charge carriers to recombine and current to flow through the diode.