In a p-n junction, the width of the depletion layer changes depending on whether it is forward biased or reverse biased:

(i) Forward Biased:

• When a p-n junction is forward biased, the width of the depletion layer decreases.
• In forward bias, the positive terminal of the voltage source is connected to the p-type region, and the negative terminal is connected to the n-type region. This causes the majority carriers (holes in the p-type region and electrons in the n-type region) to move towards the junction.
• As the majority carriers move towards the junction, they neutralize some of the immobile ions in the depletion region, reducing the width of the depletion layer.
• The reduced width of the depletion layer allows for easier flow of current through the junction.

(ii) Reverse Biased:

• When a p-n junction is reverse biased, the width of the depletion layer increases.
• In reverse bias, the positive terminal of the voltage source is connected to the n-type region, and the negative terminal is connected to the p-type region. This creates an electric field that repels majority carriers away from the junction.
• As majority carriers are pushed away from the junction, the immobile ions in the depletion region create a larger electric field, widening the depletion layer.
• The widened depletion layer restricts the flow of current through the junction, resulting in very little current flow under reverse bias conditions.

In summary, forward biasing reduces the width of the depletion layer, facilitating current flow, while reverse biasing increases the width of the depletion layer, limiting current flow.