Abstract: A gate turn-off thyristor comprising, a first emitter layer of one conductivity type, a main base layer of another conductivity type connected to said first emitter layer and a control base layer of the first conductivity type connected to the main base layer. A second emitter of the other conductivity type is connected to the control base layer at a junction which surrounds a portion of the second emitter layer. An emitter contact is connected to the second emitter layer and a control base contact is connected to the control base layer. The gate turn-off thyristor is turned off by a short circuiting of the control base contact with the emitter contact. The surface resistance of the control base layer between the second emitter layer and the control base contact is selected so that, with a control base turn-off current applied which is sufficient for turning off the thyristor, a potential appears on a lateral resistance in the control base layer which is less than a potential appearing at the junction.

Abstract: The negative temperature coefficient effect, which results in destructive current flow above a certain temperature in a semiconductor device is counteracted by a layer of conductive material that has low resistance at normal temperatures but has a positive temperature coefficient that causes its resistance to rise to a high value at temperatures below the certain temperature. The layer is applied to electrodes of semiconductor devices to control current flowing therethrough.

Abstract: A semiconductor switch including a main thyristor and an auxiliary thyristor which can both be switched on and off by a control current. The anodes of the two thyristors are connected together and lead to a first load current terminal for the switch, the cathode of the main thyristor leads to a second load current terminal for the switch, the control electrode of the main thyristor is connected with the cathode of the auxiliary thyristor, and the control current for the switch is fed in via the control electrode of the auxiliary thyristor. The turn-off gain of the main thyristor is greater than the turn-off gain of the auxiliary thyristor and the holding current of the auxiliary thyristor is lower than the holding current of the main thyristor.

Abstract: A gate turn-off thyristor device including a gate turn-off main thyristor and a gate turn-off auxiliary thyristor, each having an emitter, a control base, a main base and a counter-emitter, integrated in a semiconductor body including three zones of alternatingly opposite conductivity type. The three zones of the semiconductor body are each divided into two regions to provide the counter-emitter, main base and control base zones of the two thyristors, while the emitter zones of the main thyristor and of the auxiliary thyristor are separate zones formed in the respective associated regions constituting the control base zones of the respective thyristors.