English: Energy band diagram of a typical ${\displaystyle p^{+}n}$ step p-n junction that shows electron energy versus position. ${\displaystyle E_{c}}$ is the conduction band, ${\displaystyle E_{f}}$ is the device fermi energy level, ${\displaystyle E_{i}}$ is the intrinsic Fermi level of the undoped semiconductor, and ${\displaystyle E_{v}}$ is the valence band.