Depletion layer

Depleted layer in an n-type semiconductor. 1 - metal, 2 - dielectric, 3 - depleted in the main carriers layer, 4 - n-type semiconductor

The term Depletion Layer (Depleted Layer) in semiconductor physics characterizes a lower, compared with equilibrium , concentration of the main carriers at the interface between two materials. An example is the heterointerface of two semiconductors with different bandgaps, or the metal-semiconductor interface. At the metal-insulator interface, a depletion layer can also be obtained by applying an electric field , which is the basic physical principle of the field effect transistor .