Patent Number: 
Section: claims

1. A semiconductor photodiode comprising:a substrate active depletion layer fabricated from a radioisotope of a first type of conductivity material;a thick-field oxide layer formed on the substrate layer, the oxide layer having an open center region on the substrate layer; anda dopant material of a second conductivity material, different from the first conductivity material, the dopant material formed within the open center region on the substrate layer to form a photodiode junction, including an enclosure package enclosing the semiconductor diode for containing any radiation from the radioisotope such that initial emission of beta particles begins in the active depletion layer and substantially all of the emitted beta particles are contained within the enclosure package during operation. 2. The photodiode of claim 1 wherein the radioisotope is Si32. 3. The photodiode of claim 2 wherein the first conductivity type material is a p-type material and the second conductivity type is an n-type material. 4. The photodiode of claim 2 wherein the first conductivity type material is an n-type material and the second conductivity type is an p-type material. 5. The photodiode of claim 2 wherein the dopant is implanted into the open region. 6. The photodiode of claim 2 wherein the dopant is diffused into the open region. 7. A semiconductor photodiode comprising:a substrate active depletion layer fabricated from a Si32 radioisotope of a first type of conductivity material;a thick-field oxide layer formed on the substrate layer, the oxide layer having an center open region on the substrate layer;a dopant material of a second conductivity material, different from the first conductivity material, the dopant material formed within the open center region on the substrate layer to form a photodiode junction, andan enclosure package enclosing the semiconductor diode for containing any radiation from the radioisotope such that initial emission of beta particles begins in the active depletion layer and substantially all of the emitted beta particles are contained within the enclosure package during operation.