Question

Diffusion current is due to ___________

(a) Applied electric field over a given distance

(b) Variation in carrier concentration

(c) Random motion of holes

(d) Recombination of holes and electrons

I had been asked this question during an internship interview.

This question is from Drift and Diffusion Current in division Diode Circuit of Analog Circuits

Answer 1

Right option is (b) Variation in carrier concentration

The explanation is: Diffusion current is due to the actual movement of carrier charges from one side to another. The direction of diffusion depends on the slope of the carrier concentration that is the gradient of density of carriers.