Question

The thickness of the depletion layer is approximately
A) 1μm
B) 1mm
C) 1cm
D) 1m

Answer 1

Hint In order to solve this particular question we need to know how the depletion layer is formed in the p-n junction.
Depletion region is a region near the p-n junction where flow of charge carriers (free electrons and holes) is reduced over a given period and finally results in zero charge carriers. The width of depletion region depends on the amount of impurities added to the semiconductor. Generally, the thickness of the depletion layer is 1μm.

Complete step-by- step solution
This problem asks us about the thickness of the depletion layer. This is a very straight-forward question. Although, we need to know something about the depletion layer.
Let us consider a p-n junction diode. We can think of it in any bias either forward or reverse bias. So, in the p-n junction diode shown above, the ‘P’ side of the junction diode will contain ‘holes’ (positively charged ) in majority and the ‘N’ side of the junction diode will contain ‘electrons’ ( negatively charged ) in majority.
So, gradually the holes and the electrons will combine at the junction as holes will attract electrons towards it and the electrons attract holes towards it.
They both combine and form electron-hole recombination layers.
Due to this attraction process, the layer formed between them goes on increasing and this particular layer is only known as depletion layer.
In simpler words, depletion region / layer is the region near the p-n junction where flow of charge carriers (free electrons and holes) is reduced over a given period and finally results in zero charge carriers.
The width of the depletion layer which is generally 1ilm, depends on the amount of the impurities added to the semiconductor.
Impurities are the atoms (pentavalent and trivalent atoms) added to the semiconductor to improve its conductivity.

Hence, the answer is 1μm.and the correct option is.

Note Moving away from the junction, a depletion region is formed in the vicinity of the junction. In the depletion region, an electric field exists that quickly sweeps out electron-hole pairs that may be thermally generated and reduces the equilibrium concentration of the charge carriers to exceedingly low levels.