Question

A potential barrier of 0.5 V exists across a pn-junction having depletion region (0.8 $\mu$m wide). An electron approaches from n-side with K.E 0.6 eV. Find E in depletion region and K.E of electron when it enters p-side.

• A. $E=6.25\times {10}^{5}V/m,K.E=1.1eV$
• B. $E=6.25\times {10}^{5}V/m,K.E=0.1eV$
• C. $E=6.25\times {10}^{6}V/m,K.E=0.1eV$
• D. $E=6.25\times {10}^{6}V/m,K.E=1.1eV$

Answer 1

The correct option is B $E=6.25\times {10}^{5}V/m,K.E=0.1eV$

$E=\frac{\Delta V}{d}=\frac{0.5}{0.8\times {10}^{-}6}=\frac{5}{8}\times {10}^6=6.25\times {10}^{5}V/m$

$K.E=0.1eV$ (Due to retarted motion, K.E decreases)