Patent Number: 
Section: claims

1. A Betavoltaic cell comprising:a SiC substrate;structures formed of semiconductor, wherein the structures comprise p-n junctions, and wherein there are voids proximal to the structures; andelectrical contacts formed on the structures, wherein the contacts are adapted to minimize beta radiation backscatter losses. 2. The Betavoltaic cell of claim 1 and further comprising a beta radiation source. 3. The Betavoltaic cell of claim 2 wherein the beta radiation source is disposed on the surface of the structures. 4. The Betavoltaic cell of claim 2 wherein the beta radiation source comprises Ni-63, or tritium (H-3), or Promethium, or combinations thereof. 5. The Betavoltaic cell of claim 1 wherein the contacts occupy about 1% of an active device area of the p-n junctions. 6. The Betavoltaic cell of claim 2 wherein the radiation source comprises beta radiation producing particles and wherein a semiconductor surface area for accepting the radioactive particles is smaller than an overall device surface area. 7. The Betavoltaic cell of claim 1 wherein the p-n junctions are formed from n doped semiconductor disposed underneath p doped semiconductor or a p doped semiconductor disposed underneath n doped semiconductor. 8. The Betavoltaic cell of claim 1 wherein the structures are formed of high aspect ratio SiC. 9. The Betavoltaic cell of claim 1 wherein the aspect ratio of the structures is at least 10:1. 10. The Betavoltaic cell of claim 1 wherein the aspect ratio of the structures is at least 500:1 or less. 11. The Betavoltaic cell of claim 1 wherein the structures comprise pillars. 12. A Betavoltaic cell comprising:a semiconductor substrate;at least one p-n junction formed of semiconductor; andat least one contact electrically coupled to the at least one p-n junction, wherein the at least one contact is adapted to minimize beta radiation backscatter losses. 13. The Betavoltaic cell of claim 12 and further comprising a beta radiation source. 14. The Betavoltaic cell of claim 13 and further comprising at least one structure formed of semiconductor. 15. The Betavoltaic cell of claim 14 wherein the beta radiation source is disposed on the surface of the at least one structure. 16. The Betavoltaic cell of claim 13 wherein the beta radiation source comprises Ni-63, or tritium (H-3), Promethium, or combinations thereof. 17. The Betavoltaic cell of claim 12 wherein the at least one contact occupies about 1% of an active device area of the p-n junctions. 18. The Betavoltaic cell of claim 12 wherein the at least one p-n junction is formed from n doped semiconductor disposed underneath p doped semiconductor or a p doped semiconductor disposed underneath n doped semiconductor. 19. A Betavoltaic cell comprising:a SiC substrate;high aspect ratio pillars supported by the substrate having voids between the pillars;cathode or anode contacts formed on the pillars, wherein the cathode or anode contacts are adapted to minimize beta radiation backscatter losses;an anode or cathode contact formed on a back side of the substrate; anda beta radiation fuel disposed in the voids. 20. The Betavoltaic cell of claim 19 wherein the beta radiation fuel comprises Ni-63, or tritium (H-3), or Promethium or combinations thereof. 21. The Betavoltaic cell of claim 19 wherein the high aspect ratio pillars are formed from n doped semiconductor disposed underneath p doped semiconductor or a p doped semiconductor disposed underneath n doped semiconductor. 22. A Betavoltaic cell comprising:a semiconductor substrate;structures formed of semiconductor, wherein the structures comprise p-n junctions, and wherein there are voids proximal to the structures;cathode or anode contacts formed on the structures, wherein the cathode or anode contacts are adapted to minimize beta radiation backscatter losses;an anode or cathode contact formed on a back side of the substrate; anda cap formed of semiconductor. 23. The Betavoltaic cell of claim 22 and further comprising a beta radiation source in the voids. 24. The Betavoltaic cell of claim 23 wherein the beta radiation source comprises Ni-63, or tritium (H-3), or Promethium, or combinations thereof. 25. The Betavoltaic cell of claim 22 wherein the p-n junctions are formed from n doped semiconductor disposed underneath p doped semiconductor or a p doped semiconductor disposed underneath n doped semiconductor. 26. The Betavoltaic cell of claim 22 wherein the structures are formed of high aspect ratio SiC. 27. The Betavoltaic cell of claim 22 wherein the aspect ratio of the structures is approximately 10:1 or less. 28. The Betavoltaic cell of claim 22 wherein the aspect ratio of the structures is approximately 500:1 or less. 29. The Betavoltaic cell of claim 22 wherein the structures comprise pillars.