Thyristor with amplified firing current

Claim 1

A semiconductor device of the thyristor type comprising a body of semiconductive material having first, second and third superposed doped semiconductor layers which alternate in their type of semiconductivity, said second layer which is disposed between said first and third layers being of a first type of semiconductivity and said first and third layers being of a second type of semiconductivity, an emitter layer formed centrally within the top surface of said first layer and which has said first type of semiconductivity so as to establish a p-n junction therebetween, a first main electrode establishing contact with said emitter layer, said emitter layer also being provided with a central opening within which a gating electrode is connected to a highly doped central zone of said first layer, an annular zone formed in the top surface of said first layer concentrically within said central opening in said emitter layer and surrounding said gating electrode, said annular zone having said first type of semiconductivity so as to establish a p-n junction therebetween, an electrical contact member in contact with and linking an edge portion only of said annular zone with a contiguous portion of the top surface of said first layer to establish an auxiliary shorted emitter, said emitter layer being provided also with at least one additional opening establishing a corresponding zone of said first layer within which is provided a small area highly doped contact zone of the same type semiconductivity as said first layer and which serves as an auxiliary gating electrode, an electrical conductor directly connecting said annular zone with said small area contact zone, and a second main electrode establishing contact with a highly doped surface region of said third layer.