We induce localized high carrier concentration at end of sla

We induce localized high carrier concentration at end of slab of uniform doped Si without creating electric field. What kind of current we see?

a) Diffusion current toward increasing carrier concentration.

b) Diffusion current away from increasing carrier concentration.

c) Drift current as result of covalent bonding between dopant and Si.

d) None.

Solution

If we induce high carrier concentration at one end of slab then concentration gradient will occur .that is nothing but one end is at high concentration and other end at low concentration so charges move high concentration level to low concentration level this current is diffusion current.so current is moving away from increasing carrier concentration... So ans is option is b