When a p-n junction is reverse-biased,the current becomes almost constant at 25µA. current of when it is forward biased at 200 mV . a current of 75µA is obtained.Find the magnitude of diffusion current when the diode is (a)unbiased ,(b)reverse-biased at 200 mVand (c )forward-biased at 200mV.

Explanation

Given `i_1 = 25muA`
`V = 200mV, i_2 = 75muA`
(a) When in unbiased condition drift current `=` diffusion current
`:.` Diffusion Current `=-25muA`
(b) On Reverse biasing the diffution current becomes `0`.
(c ) On forward biasing the actual current be `x`.
`x- Drift Current = forward biasin current`
`rArr x-25muA = 75muA`
`rArr x = (75+25)muA`
` = 100muA