Question

A potential barrier of 0.5 V exists across a p-n junction (i) If the depletion region is $5\times {10}^{-7}$ m wide. What is the average intensity of the eectric field in this region? (ii) An electron with speed $5\times {10}^5$ m/s approaches the p-n junction from the n-side with what speed will it enter the p-side?

Answer 1

An electron from the n-side into the p-n junction through the depletion region and when it reaches the p-side it gains energy equal to exponential barriers.

By conservation of energy,

KE before entering =ev +KE after reaching p side

$12\times m\times V21=e\times 0.5+12\times m{V}_2^2$

Solving we get,

$V2=2.7\times {10}^{5}m/s$