Radiation sensitive thyristor structure with isolated detector

A radiation sensitive semiconductor device comprising:

• a semiconductor substrate;
• a radiation sensitive region on said substrate operative to generate an electrical current in response to the incidence of radiation thereon;
• a gate region responsive to the flow of current therein to turn on said semiconductor device;
• an isolating region interposed between said radiation sensitive region and said region for increasing the lateral resistance of said substrate layer between said radiation sensitive region and said gate region to a value greater than the lateral resistance of the remainder of said substrate, said isolating region further characterized by a region of locally higher base resistance than the remainder of said substrate surrounding said radiation sensitive region and by a lower impurity concentration than the remainder of said substrate layer;
• and
• means for coupling said electrical current from said radiation sensitive region to said gate region for turning on said device in response to the incidence of radiation on said radiation sensitive region.