Gate turn-off thyristor with independent turn-on/off controlling transistors

Claim 1

A gate turn-off thyristor comprising: (a) a semiconductor substrate of a first conductivity type serving as a first base layer; (b) a first emitter layer and a second base layer both of a second conductivity type, which are formed on opposing surfaces of said substrate; (c) a second emitter layer of the first conductivity type formed in said second base layer, said second emitter layer at least partially having a substantially rectangular slender planar shape defined by long and short sides; (d) a first metal oxide semiconductor field effect transistor of a certain channel conductivity type for performing a switching operation to turn on said thyristor, said first transistor having a channel region formed along the short side of said second emitter layer, said first transistor comprising, a first semiconductor layer of the first conductivity type formed in said second base layer to serve as a source of said first transistor and to define a surface portion of said second base layer positioned between itself and said first base layer as a channel region of said first transistor, and a first gate electrode layer insulatively provided above said first base layer to cover said channel region; (e) a second field effect transistor for performing a switching operation to turn off said thyristor by short-circuiting said first base layer and said second emitter layer, said second transistor having a channel region which is formed along the long sides of said second emitter layer to have a channel width which is greater than that of said first transistor, said second transistor comprising, a second semiconductor layer of the first conductivity type formed in said second base layer to serve as a drain of said second transistor, said second semiconductor layer defining a surface portion of said second base layer positioned between itself and said second emitter layer as a channel region of said second transistor, and a second gate electrode layer insulatively provided above said channel region of said second transistor; and (f) a source electrode layer formed on said second base layer, for causing said source and said drain to be electrically conductive together with said second base layer, whereby said source electrode layer serves as an amplifying gate electrode of said first transistor, sao that a source current of said first transistor acts as a base current of said thyristor to improve a gate sensitivity thereof.