The depletion region of p-n junction has a thickness of the order of

The correct answer is Option (3) → \( 10^{-7}\,\mathrm{m} \)

The depletion region of a p-n junction is very thin, about one-tenth of a micrometre:

    \( 0.1\,\mu\mathrm{m} = 0.1\times10^{-6}\,\mathrm{m} = 10^{-7}\,\mathrm{m} \)

It is thin because the immobile ions it contains set up a strong field (the barrier potential of a few tenths of a volt across about \( 10^{-7} \) m) that soon stops further diffusion.

NCERT (2026-27):
p-n Junction Formation – “… This space-charge region on either side of the junction together is known as depletion region as the electrons and holes taking part in the initial movement across the junction depleted the region of its free charges (Fig. 14.10). The thickness of depletion region is of the order of one-tenth of a micrometre.”