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 electric field is `E=V//d`
`=(0.50V)/(5.0xx10^(-7)m)=1.0xx10^(6)V//m`
(b)
Suppose 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 x 0.50 V, from the principle of conservation of energy.
`(1)/(2)mupsilon_(1)^(2)=exx0.50+(1)/(2)mupsilon_(2)^(2)`
`(1)/(2)(9.1xx10^(-31))(5xx10^(5))^(2)`
`=1.6xx10^(-19)xx0.5+(1)/(2)xx9.1xx10^(-31)xxupsilon_(0)^(2)`
Solving this, `upsilon_(2)=2.7xx10^(5)m//s`.