Question

In an unbiased \( p\)-\( n \) junction, electrons diffuse from \( n\)-region to \( p\)-region because:

• A. holes in \( p\)-region attract them
• B. electrons travel across the junction due to potential difference
• C. only electrons move from \( n\)-region to \( p\)-region and not the vice-versa
• D. electron concentration in \( n\)-region is more compared to that in \( p\)-region

Hint:

In an unbiased \( p\)-\( n \) junction, the concentration gradient causes electrons to diffuse from the \( n\)-region to the \( p\)-region, resulting in a depletion region and an opposing electric field.

Answer 1

The Correct Option is D

In an unbiased \( p\)-\( n \) junction:
The \( n\)-region exhibits a markedly greater electron density than the \( p\)-region.
This disparity in concentration drives electron diffusion from the \( n\)-region (high density) to the \( p\)-region (low density).
This charge carrier movement leads to the formation of a depletion region, wherein an electric field arises.
The intrinsic electric field impedes further electron migration, thus achieving equilibrium.


Final Answer:
\[\boxed{\text{electron concentration in the \( n\)-region is higher than in the \( p\)-region}}\]