Question

When a p-n junction diode is forward biased:

• A. the barrier height and the depletion layer width both increase.
• B. the barrier height increases and the depletion layer width decreases.
• C. the barrier height and the depletion layer width both decrease.
• D. the barrier height decreases and the depletion layer width increases.

Hint:

Forward biasing a diode reduces the barrier to charge flow, enabling current to pass through the junction, which is the basis of diode operation in electronic circuits.

Answer 1

The Correct Option is C

Solution: When a p-n junction diode is forward biased, the application of an external voltage reduces the potential barrier. Let's break down the effects:

1. Barrier Height: In a forward-biased condition, the external voltage applied across the diode reduces the electric field within the depletion region. This reduction in the electric field lowers the barrier height. Electrons and holes can more easily cross the junction, leading to increased current flow. Thus, the barrier height decreases.
2. Depletion Layer Width: The forward-bias condition reduces the width of the depletion region. The applied voltage provides energy that lessens the barrier to carrier movement. Consequently, more charge carriers are injected into the region, and the electric field is weakened, resulting in a decrease in depletion layer width.

Therefore, when a p-n junction diode is forward biased, the barrier height and the depletion layer width both decrease.