A potential barrier of 0.50V exists across a p-n junction.(a) If the depletion region is `5.0xx10^(-7)`m wide,what is the intensity of the electric field in this region?(b) An electron with speed`5.0xx10^(5)m s^(-1)`approaches the p-n junction form the n-side.With what speed will it enter the p-side?

Explanation

(a) The eletric field is `E = V//d`
=`(0.5 V)/(5.0xx10^(-7)m) =1.0 xx 10^(6) V//m`
(b)
Let the electron has a speed `v_(1)` when it enters the depletion layer and `v_(2)` when it comes out of it. As the potential energy increases by `e xx 0.50 V`. From the principle of conservation of energy
`(1)/(2) m upsilon_(1)^(2) = e xx 0.50 + (1)/(2) m upsilon_(2)^(2)`
`(1)/(2) (9.1 xx 10^(-31)) (5 xx 10^(5))^(2)`
`= 1.6 xx 10^(-19) xx 0.5 + (1)/(2) xx 9.1 xx 10^(-31) xx upsilon_(2)^(2)`
Solving this, `upsilon_(2) = 2.7 xx 10^(5) m//s`.