Semiconductor device and circuit arrangement comprising the device

Claim 1

A semiconductor device comprising a semiconductor body containing at least one transistor, said transistor comprising a surface base region of a first conductivity type adjacent a major surface of the body, and surface collector and emitter zones of a second conductivity type also adjacent said major surface and being separated from each other by the said base region, at least one further region of the second conductivity type in the body and separated by the base region from the emitter and collector zones, means for applying a potential to the collector zone for reverse biasing the junction between it and the base region thereby establishing a depletion zone which extends from the collector-base junction into the base region towards both the emitter zone and said further region, the spacing between the collector zone and the said further region and the emitter zone and the dopant concentration of the base region extending therebetween being such that at a given threshold value of the said reverse potential the depletion zone reaches-through to the said further region before it reaches-through to the emitter zone, said further region having a portion extending beneath the collector zone and beneath the emitter zone, whereby below the threshold potential value the transistor operates as a lateral transistor of relatively low gain and above the threshold potential value the transistor operates as a transverse transistor of relatively high gain.