Patent Number: 
Section: claims

1. A device for producing electricity, comprising:a germanium substrate doped a first dopant type;a plurality of stacked material layers extending from the substrate, further comprising:a base layer doped the first dopant type;an emitter layer doped the second dopant type;a window layer having a lattice structure matched to the lattice structure of the emitter layer and doped the second dopant type; anda beta particle source for generating beta particles;wherein the plurality of stacked material layers further comprise an InAlP reflector layer doped the first dopant type and disposed between the substrate and the base layer. 2. The device of claim 1 wherein the plurality of stacked material layers further comprises a GaAs layer doped the first dopant type and disposed between the substrate and the base layer for serving as a nucleation layer or as a layer for establishing the crystal structure. 3. The device of claim 1 wherein the plurality of stacked material layers further comprise an intrinsic InGaP layer disposed between the base layer and the emitter layer. 4. The device of claim 1 further comprising a physical barrier for shielding edges of the plurality of stacked material layers from the beta particles. 5. A device for producing electricity, comprising:a germanium substrate doped a first dopant type;a plurality of stacked material layers extending from the substrate, further comprising:a base layer doped the first dopant type;an emitter layer doped the second dopant type;a window layer having a lattice structure matched to the lattice structure of the emitter layer and doped the second dopant type; anda beta particle source for generating beta particles;wherein the plurality of stacked material layers further comprise a GaAs cap layer doped the second dopant type and having a higher doping level than the emitter layer, the GaAs cap layer disposed between the window layer and the beta particle source. 6. The device of claim 5 wherein the bandgap of the window layer is greater than the band gap of the emitter layer. 7. The device of claim 5 wherein the first dopant type comprises a p dopant type and the second dopant type comprises an n dopant type or wherein the first dopant type comprises an n dopant type and the second dopant type comprises a p dopant type. 8. The device of claim 5 wherein a material of the window layer comprises one of InAlP, InAlGaP, ZnSe, AlAs, AlAsP, and a pseudomorphic layer. 9. The device of claim 5 wherein a material of the beta particle source comprises one of InAlP, AlGaP, and InGaP, tritium metal hydride and a polymer containing tritium. 10. The device of claim 5 wherein a material of the base layer comprises one of InGaP, In(AlGa)P, and InAlP and a material of the emitter layer comprises one of InGaP, In(AlGa)P, and InAlP. 11. A device for producing electricity, comprising:a germanium substrate doped a first dopant type;a plurality of stacked material layers extending from the substrate, further comprising:a base layer doped the first dopant type;an emitter layer doped the second dopant type;a window layer having a lattice structure matched to the lattice structure of the emitter layer and doped the second dopant type;a beta particle source for generating beta particles; anda housing, wherein the device is hermetically sealed within the housing. 12. A device for producing electricity, comprising:a germanium substrate doped a first dopant type;a plurality of stacked material layers extending from the substrate, further comprising:a base layer doped the first dopant type;an emitter layer doped the second dopant type;a window layer having a lattice structure matched to the lattice structure of the emitter layer and doped the second dopant type;a beta particle source for generating beta particles; anda first terminal comprising a contact ring disposed on a surface of the plurality of stacked material layers. 13. A device for producing electricity, comprising:a germanium substrate doped a first dopant type;a plurality of stacked material layers extending from the substrate, further comprising:a base layer doped the first dopant type;an emitter layer doped the second dopant type;a window layer having a lattice structure matched to the lattice structure of the emitter layer and doped the second dopant type; anda beta particle source for generating beta particles;wherein the substrate is doped a p dopant type, the base layer is doped an n dopant type and the emitter layer is doped the p dopant type, the device further comprising a p dopant type tunnel junction layer adjacent an n dopant type tunnel junction layer disposed between the substrate and the base layer with the p dopant type tunnel junction layer disposed closer to the substrate than the n dopant type tunnel junction layer. 14. A device for producing electricity, comprising:a germanium substrate doped a p dopant type;a plurality of stacked material layers extending from the substrate, further comprising:a GaAs first layer doped the p dopant type;an InGaP base layer doped the p dopant type;an InGaP emitter layer doped an n dopant type; andan InAlP window layer having a lattice structure matched to the lattice structure of the emitter layer and doped the n dopant type;a GaAs cap layer doped the n dopant type;an InAlP reflector layer doped the p dopant type and disposed between the substrate and the base layer; anda beta particle source for generating beta particles. 15. The device of claim 14 wherein the plurality of stacked material layers further comprise an intrinsic InGaP layer disposed between the base layer and the emitter layer. 16. The device of claim 14 wherein the GaAs first layer has a higher doping concentration than the base layer. 17. A device for producing electricity, comprising:a beta particle source layer for generating beta particles that travel in opposing directions from the beta particle source layer;a plurality of stacked material layers on each one of two opposing surfaces of the beta particle source layer;each of the plurality of stacked material layers comprising:a germanium substrate doped a first dopant type;a base layer doped the first dopant type;an emitter layer doped the second dopant type; anda window layer having a lattice structure matched to the lattice structure of the emitter layer. 18. The device of claim 17 wherein a material of the base layer comprises one of InGaP, In(AlGa)P, and InAlP and a material of the emitter layer comprises one of InGaP, In(AlGa)P, and InAlP.