Physics - Semiconductors Question with Solution | TestHub

The diffusion current in a p--n junction is greater than the drift current in magnitude only under forward bias.

At equilibrium (unbiased),

$$J_{diff}=J_{drift},$$

so neither is greater.

Under forward bias, injected minority carriers produce a much larger diffusion current,

$$J_{diff}\propto e^{qV/kT},$$

while the drift current remains small. Hence diffusion current dominates.

Under reverse bias, the drift current dominates and the diffusion current is very small.

So correct option is If the junction is forward biased.