Question

The $n$ -side of the depletion layer of a $p-n$ junction

• A. always has same width as of the p-side
• B. has no bound charges
• C. is negatively charged
• D. is positively charged

Answer 1

Answer: (D)

Depletion layer is formed due to diffusion of electrons from $n$-side to $p$-side. There they combine with holes of $p$-side.

In a $p-n$ junction, there are no free charges in depletion region. It contains only bound charges. Width of depletion region is inversely proportional to dopant concentration. So, it may have different width in $p$ and $n$-sides. Due to diffusion of electrons, $p$-side is negatively charged and n-side is positively charged.