Diffusion Current — DirectionHardQuestion 20216
Question
In a p-n junction with no external bias, the net current is zero because:
- ANo carriers exist in the depletion region
- BDrift current and diffusion current exactly balance each otherCorrect
- CAll carriers are immobile
- DThe junction has infinite resistance
Correct answer
Drift current and diffusion current exactly balance each other
Explanation
Diffusion of majority carriers across the junction builds a potential barrier (contact potential). The barrier creates a drift current (minority carriers swept by built-in field) that exactly opposes the diffusion current → equilibrium with zero net current.