English: A PN junction in thermal equilibrium with zero bias voltage applied. Electron and hole concentrations are reported respectively with blue and red lines. Gray regions are charge neutral. Light red zone is positively charged.

Light blue zone is negatively charged. Under the junction, plots for the charge density, the electric field and the voltage are reported.

Note that the image depicts the red depletion region in the N-doped material going deeper (with a greater area) than the blue depletion region in the P-doped material, which is explained by a higher N-doped density.