Deep depletion semiconductor device with surface inversion preventing means

Claim 1

A semiconductor insulated gate field-effect transistor comprising a semiconductor body having a layer-shaped region of a first conductivity type adjoining a surface of the body, spaced source and drain electrodes at the said body surface forming a main current path therebetween in the layer-shape region and adjacent the said surface, an electrically insulating layer on at least part of said surface, a gate electrode layer on said insulating layer and over the main current path in said layershaped region, means for applying to said gate electrode layer a potential relative to the source electrode and tending to establish a depletion zone in said layer-shaped region extending inward from the said surface in order to modify the electric resistance of the main current path of said layer-shaped region in a direction parallel to the surface, and means for preventing the formation of an inversion layer below the electrode layer inhibiting the inward extension of said depletion zone, said inversion layer preventing means comprising a rectifying contact to the layer-shaped region and located outside the main current path between the source and drain but substantially within a minority carrier diffusion length of where the inversion layer may be formed, means for applying to the said rectifying contact a reverse bias for draining generated minority carriers from said layer-shaped region thereby preventing the formation of said inversion layer, and means for applying a control voltage to the gate.