Semiconductor particle-detector

A particle-detector formed on a die of semiconductor material comprising:

• a first layer with a first type of conductivity having a surface on the front face of the die,
• a second layer with the first type of conductivity having a surface on the rear face of the die,
• a third layer with a second type of conductivity interposed between the first and second layers and extending laterally only to a certain distance from the edge of the die,
• first and second means for electrical connection with said first layer and said second layer, respectively, disposed on the surfaces thereof, and
• third means for electrical connection with the third layer,
• wherein the third electrical connection means comprise a region with the second type of conductivity which extends from the front face of the die as far as the third layer and means for surface electrical contact with this region;
• wherein said certain distance between the edge of the die and said third layer is chosen so that a depletion region formed between said third and said second layers during operation of said particle-detector does not reach the sidewall of the die.