Question

Calculate the diffusion current density when the concentration of electron varies from the 1*10^18 to 7*10^17 cm^-3 over a distance of 0.10 cm.D=225cm^2/s

(a) 100 A/cm^2

(b) 108 A/cm^2

(c) 0.01A/cm^2

(d) None

This question was addressed to me in a job interview.

I'm obligated to ask this question of Diffusion topic in chapter Conduction in Semiconductors of Electronic Devices & Circuits

Answer 1

Correct choice is (b) 108 A/cm^2

The best explanation: J=eDdn/dx

J=1.6*10^-19*225*(10^18-(7*10^17))/0.1

=108A/cm^2.