A potential barrier of 0.4V exists across a p-n junction. If the depletion region is `4.0xx10^(-7)m` wide, what is the intensity of the electric field in this region? If an electron with speed `4.5xx10^(5)m//s` approaches the p-n junction from the n-side, find the speed with which it will enter the p-side.

Explanation

(i) Width of depletion layer `DeltaL=5 times 10^(-7)m`
`E=V/(DeltaL)=(0.5 V)/(5 times 10^(-7))=10^(6)` volt/m

(ii) Work energy theorm `1/2 Mv_(i)^(2)=eV+1/2Mv_(f)^(2)`
`v_(f)=sqrt((Mv_(i)^(2)-2eV)/M)=2.7 times 10^(5)m//s`