Question

When a p-n junction diode is forward biased, the:

• 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:

In a forward biased diode, the barrier height decreases and the depletion region narrows, allowing current to flow more easily.

Answer 1

The Correct Option is C

To understand the behavior of a p-n junction diode when it is forward biased, let's explore the concepts of barrier height and depletion layer width: 

A p-n junction diode consists of p-type and n-type semiconductors. At the junction, there is a built-in potential barrier that prevents charge carriers from crossing over. The barrier height is the energy level that must be overcome for the charge carriers to move across the junction.

When a diode is forward biased:

• The external voltage reduces the barrier height. This makes it easier for the electrons from the n-side to recombine with holes on the p-side and vice versa.
• The depletion layer, the region devoid of charge carriers, shrinks because the forward bias provides energy that helps the electrons and holes recombine more efficiently, neutralizing the charges in this region.

Thus, under forward bias conditions, the observed effects on the p-n junction diode are: a decrease in both the barrier height and the depletion layer width. The correct answer is:

The barrier height and the depletion layer width both decrease.