Patent Number: 
Section: claims

1. An electrical power source comprising a semiconductor, the semiconductor comprising a diamond material and a radioactive source embedded within the diamond material, wherein the radioactive source comprises a beta-emitting radioisotope and atoms of the radioisotope are substitutionally or interstitially integrated into the diamond material,wherein the diamond material comprises a plurality of regions in the form of layers within a continuous crystal lattice of the diamond material, andwherein at least one layer of the diamond material comprises the radioactive source and at least one layer of the diamond material does not comprise the radioactive source. 2. The electrical power source of claim 1, wherein the radioactive source embedded within the diamond material is formed of one or more of tritium, 14C, 10Be and phosphorus-33. 3. The electrical power source according to claim 1, wherein the diamond material has a layered structure with at least one layer comprising the radioactive source and at least one layer which does not comprise the radioactive source. 4. The electrical power source according to claim 1, wherein the radioactive source is provided in a layer of diamond having a thickness in a range 50 nanometres to 150 micrometres. 5. The electrical power source according to claim 1, wherein the diamond material includes a 13C diamond region which comprises isotopically purified diamond material having an increased 13C content compared to natural isotopic abundance. 6. The electrical power source according to claim 5, wherein the 13C diamond region is in the form of a layer having a thickness in a range 2 nanometres to 2 millimetres. 7. The electrical power source according to claim 5, wherein the 13C diamond region has an atomic concentration of 13C of at least 2%, 3%, 4%, 5%, 10%, 20%, 50%, 75%, 85%, 95%, 99%, or 99.9%. 8. The electrical power source according to claim 1, wherein the diamond material includes a 12C diamond layer comprising a boron-doped 12C diamond layer. 9. The electrical power source according to claim 8, wherein the 12C diamond layer has a thickness in a range 200 nanometres to 2 millimetres. 10. The electrical power source according to claim 1, wherein the diamond material includes a tri-layer structure comprising a layer of 14C containing diamond, a layer of 12C diamond, and a layer of 13C diamond. 11. The electrical power source according to claim 1, wherein the diamond material has a layered structure comprising one or more layers of the diamond material, and wherein at least one layer of the one or more layers comprises an isotopic layer within the diamond material. 12. The electrical power source according to claim 1, wherein the diamond material has a single substitutional nitrogen concentration of no more than 5 ppm, 1 ppm, 500 ppb, 300 ppb or 100 ppb in at least one region thereof. 13. The electrical power source according to claim 1, wherein the diamond material in which a radioactive source is embedded is a synthetic diamond material in which radioisotope atoms are integrated during formation of the synthetic diamond material.