Four-region switching transistor comprising a controlled current path in the emitter

Claim 1

A CONTROLLED RECTIFIER COMPRISING A WAFER OF SEMICONDUCTOR MATERIAL HAVING A REGION OF ONE CONDUCTIVITY CHARACTERISTICS AND TWO END REGIONS OF OPPOSITE CONDUCTIVITY CHARACTERISTIC WITH THE REGIONS ARRANGED TO PROVIDE TWO P-N JUNCTIONS IN THE WAFER, A FURTHER REGION WHICH SERVES AS THE EMITTER REGION TO SAID RECTIFIER EXTENDING OVER A SUBSTANTIAL PART OF THE SURFACE OF ONE OF SAID END REGIONS AND FORMING A PN JUNCTION THEREWITH, AN ELECTRODE IN OHMIC CONTACT WITH SAID FURTHER REGION, A TRIGGER ELECTRODE IN OHMIC CONTACT WITH SAID END REGION, AND A BASE ELECTRODE IN OHMIC CONTACT WITH THE SURFACE OF THE OTHER END REGION OF THE WAFER, WITH SAID FURTHER REGION BEING SHAPED TO PROVIDE A NARROW FINGER WHICH EXTENDS TOWARD THE TRIGGER ELECTRODE AND IS THE PART OF THE REGION CLOSEST THERETO, WHEREBY SUBSTANTIALLY ALL OF THE CURRENT WHICH FLOWS BETWEEN SAID TRIGGER ELECTRODE AND THE FURTHER REGION PASSES THROUGH THE PN JUNCTION BETWEEN THE INGER AND THE END REGION.