layer, depletion (1) (associated with a p-n semiconductor junction)

A region whose conductivity type on each side of the junction is the same as that produced by the net fixed charged density of ionized donors and acceptors but whose net carrier density is insufficient for neutralization due to the built-in potential barrier of the p-n junction and, if present, an applied reverse bias.

(2) (associated with a surface): A surface region of a semiconductor device whose conductivity type is the same as that produced by the net fixed charge density of ionized donors and acceptors but whose net carrier density is insufficient for neutralization due to charge carrier attraction.

NOTE The charge carrier attraction may be caused by a field-plate voltage such as in field-effect transistors or by unwanted charge residing in surface states, insulating layers, or surface ionic species.

References