Before revision: Example where D is the diffusion coefficient for the electron in the considered medium, n is the number of electrons per unit volume (i.e.
After revision: To derive the diffusion current in a semiconductor diode, the depletion layer must be large compared to the mean free path.One begins with the equation for the net current density J in a semiconductor diode,Example where D is the diffusion coefficient for the electron in the considered medium, n is the number of electrons per unit volume (i.e.