Question

When a $p-n$ junction diode is reverse biased, then

• A. no current flows
• B. the depletion region is increased
• C. the depletion region is reduced
• D. the height of the potential barrier is reduced

Answer 1

Answer: (B)

the depletion region is increased

Answer 2

In reverse biasing, the applied voltage $V$ on the $n$-side is positive and is negative on the $p$-side. The applied bias $V$ and the barrier potential $V _{ B }$ are in the same direction making the effective junction potential $V + V _{ B }$. As a result, the junction width will increase. The higher junction potential would restrict the flow of majority carriers to a much greater extent. However, such a field will favour the flow of minority carriers. So, reverse bias current will be due to the minority carriers only.