This has to do with PN junctions I am really confused about

This has to do with PN junctions. I am really confused about the behaviors the currents and directions of the electrons and holes go in. Could you please explain the relationship of their behaviors?

Electrons and holes are distributed as a function of distance as below. Please sketch directions of electrons or holes, and corresponding currents.(10pts) Direction of hole: Direction of current Direction of hole: Direction of current Direction of electron Direction of current Direction of electron Direction of current

Solution

in pn junction diode current is mainly due to drift and difflusion

in difflusion current flows due to concentration gradient

the current direction is the direction of holes difflusion and opposite to the electron difflusion

in case 1 hole concentration increases from left to right hence holes diffluses from right to left hence curren direction also from right to left

in case2 hole concentration increases from right to left hence holes diffluses from left to right hence curren direction also from left to right

in case 3 electron concentration increases from left to right hence electron diffluses from right to left hence curren direction is from left to right

in case 4 electron concentration increases from right to left hence electron diffluses from left to right hence curren direction is from right to left