when it comes to pn junction in diode, p and n are doping semiconductors. if P and N semiconductor are contacting each other, some holes in P and some electron in N are combined. that is, they are recombined. this recombination caused the current, very small. I was wondering that where did this current flow. did it flow through N? or P? Another Question : in depletion layer, when the current due to the free carrier diffusion equals the current caused by the electric field, and the pn junction reaches equilibrium. I knew that electric field make the current when metal like Cu is moving back and forth between electric field. but in pn junction, how did electric field make the current?