Field-effect devices

Claim 1

A field-effect device comprising a semiconductor body in which a channel area of the device is present, a drain zone present in the body and situated adjacent the channel area, a drain electrode electrically connected to the drain zone, a gate situated over and separated from the channel area by a barrier layer, a gate connection for biasing the gate independently of the drain electrode to control by field-effect action across the barrier layer the passage of charge-carriers along a current path through said channel area, and field-relief means connected to said gate and extending above the drain zone towards said drain electrode, said drain zone having a sufficiently low doping that during operation of the device said field-relief means serve to spread the electrostatic field which occurs in this low-doped drain zone and to reduce at the body surface the magnitude of said field at the edge of said low-doped drain zone adjacent the channel area, characterized in that said field-relief means comprise a resistance layer which extends over the low-doped drain zone and is electrically connected between the gate and drain electrode free of a source electrode to permit during operation of the device the formation of a potential distribution along the resistance layer between the gate and drain electrode and over the current path in the underlying low-doped drain zone.