In a p-n junction, what happens when the junction is forward biased? (2019)

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Question: In a p-n junction, what happens when the junction is forward biased? (2019)

Options:

Correct Answer: Depletion region narrows

Exam Year: 2019

Solution:

When a p-n junction is forward biased, the depletion region narrows, allowing current to flow.

In a p-n junction, what happens when the junction is forward biased? (2019)

In a p-n junction, what happens when the junction is forward biased? (2019)

Step 1: Understand what a p-n junction is. It is a boundary between p-type and n-type semiconductor materials.
Step 2: Identify what forward biasing means. It means connecting the positive side of a power source to the p-type material and the negative side to the n-type material.
Step 3: When the p-n junction is forward biased, the electric field created by the power source pushes holes (positive charge carriers) from the p-side towards the junction.
Step 4: At the same time, electrons (negative charge carriers) from the n-side are pushed towards the junction.
Step 5: As holes and electrons move towards each other, they begin to recombine at the junction.
Step 6: This recombination reduces the width of the depletion region, which is the area around the junction that is normally free of charge carriers.
Step 7: With the depletion region narrowed, it becomes easier for current to flow through the junction.
Step 8: As a result, a significant amount of current can now flow through the p-n junction.

Forward Biasing in p-n Junctions – When a p-n junction is forward biased, the external voltage reduces the width of the depletion region, facilitating the flow of charge carriers (electrons and holes) across the junction.