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A potential barrier of 0.50 V 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 a speed of 5.0xx10^(5)m//s approaches the p-n junction from the n-side. With what speed will it enter the p-side ? |
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Answer» Solution :(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`. |
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