A potential barrier of 0.2 V exists across an unbiased p-n junction
(i) Calculate the width of the depletion region if an electric field of `10^(6) Vm^(-1)` exists in it
(ii) With what minimum kinetic energy a hole should diffuse from the p side to the n side if the junction is
(a) unbiased
(b) forward biased at 0.1 V
(c ) reverse biased at 0.1 V

Explanation

(i) Given potential barrier `V= 0.2 V`
Let d be the width of the potential barrier .Then Electric field
`E= (V)/(D)`
`rArr d= (V)/( E) = (0.2)/( 10^(6)) = 0.2 mu m`
(ii) When the p-n junction is revers biased at `0.1 V,` the reverse bias aids the potential barrier and increase it to `(0.2 + 0.1 V) = 0.3 V`
Minimum kinetic energy `E_(R) =eV`
`= 1.6 xx 10^(-19) xx 0.3 V`
`=0.3 eV`