Semiconductor thyristor devices having breakover protection

A semiconductor device comprising:

• an anode layer of semiconductor material adjacent a first surface of a body of semiconductor material, said anode layer containing one type conductivity modifiers;
• a base layer of semiconductor material within said body adjacent said anode layer, said base layer containing a number of uncompensated second type conductivity modifiers and forming a first PN junction with said anode layer at the interface therewith;
• an active gate region of semiconductor material within said body adjacent said base layer and spaced apart from said anode layer thereby, said active gate region containing a number of uncompensated said one type conductivity modifiers and forming a second PN junction with said base layer at the interface therewith, said number of uncompensated conductivity modifiers in said active gate region being less than that required to break down said second PN junction in an avalanche mode, said number of uncompensated conductivity modifiers in said active gate region being comparatively less than said number of uncompensated conductivity modifiers in said base layer;
• and
• a cathode layer of semiconductor material adjacent a second major surface, and also adjacent said active gate region, said cathode layer being spaced apart from said base layer thereby, said second surface opposing said first surface, said cathode layer containing said second type conductivity modifiers and forming a third PN junction with said active gate region at the interface therewith.