TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The photovoltaic cell further comprises an n-type emitter layer comprising a group-IV element selected from germanium (Ge), silicon (Si), silicon-germanium (SiGe), carbon-germanium (CGe), germanium-tin (GeSnP), silicon germanium tin (SiGeSn), CSiGeSn, and its combinations; and a p-type III-V semiconductor layer selected from a base layer, a back-surface-field layer, and or back-heterostructure layer, the p-type III-V semiconductor layer made from a material selected from gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), gallium indium arsenide (GaInAs), AlGaInAs, indium phosphide (InP), gallium phosphide (GaP), gallium indium phosphide (GaInP), GaInPAs, aluminum indium phosphide (AlInP), AlGaInP, indium arsenide (InAs), indium phosphorus arsenide (InPAs), aluminum indium arsenide (AlInAs), aluminum arsenide (AlAs), gallium-antimony (GaSb), gallium arsenic-antimony (GaAsSb), indium-antimony (InSb), GaInAsSb, GaInNAs, GaInNAsSb, gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), gallium indium nitride (GaInN), aluminum gallium nitride (AlGaN), aluminum indium nitride (AlInN), AlGaInN, and its combinations. It also comprises an n-type emitter layer comprising a group-IV element selected from Ge, Si, SiGe, CGe, GeSn, SiGeSn, CSiGeSn, and its combinations; and a p-type group-IV semiconductor base layer selected from Ge, Si, SiGe, CGe, GeSn, SiGeSn, CSiGeSn, and its combinations; where the composition of the n-type emitter and p-type base layer differs. The photovoltaic cell further comprises a first layer comprising a solar cell emitter layer formed from a group-IV layer; and a second layer comprising tunnel junctions formed from at least one III-V semiconductor layers, the III-V semiconductor layers selected from GaAs, AlGaAs, GaInAs, AlGaInAs, InP, GaP, GaInP, GaInPAs, AlInP, AlGaInP, InAs, InPAs, AlInAs, AlAs, GaSb, GaAsSb, InSb, GaInAsSb, GaInNAs, GaInNAsSb, GaN, AlN, InN, GaInN, AlGaN, AlInN, AlGaInN, and its combinations. It also comprises a first layer comprising a solar cell emitter layer formed from a group-IV layer; and a second layer comprising tunnel junctions formed from at least one III-V semiconductor layers, the III-V semiconductor layers selected from p+GaAs/n+GaAs tunnel junctions; p+AlGaAs/n+GaAs tunnel junctions; p+GaAs/n+AlGaAs tunnel junctions; p+AlGaAs/n+AlGaAs tunnel junctions; p+AlGaAs/n+GaInP tunnel junctions; p+AlGaAs/n+AlGaInP tunnel junctions; and p+AlGaInP/n+AlGaInP tunnel junctions. The photovoltaic cell comprises a solar cell emitter comprising a group-IV material, the emitter doped with an element selected from a column-III element and a column-V element. At least one column-IV element dopes one or more layers in a component of the cell selected from the solar cell base, the back-surface-field, the tunnel junction layers, or its combinations, and at least one region of the cell comprises at least one III-V semiconductor layer. The photovoltaic cell further comprises a first layer comprising a solar cell emitter layer comprising a group-IV layer; and a second layer comprising a tunnel junction comprising at least one group-IV semiconductor layer selected from Ge, Si, SiGe, CGe, GeSn, SiGeSn, and CSiGeSn. Preferred Process: Energy generation further involves providing a n-type emitter layer comprising a group-IV element selected from Ge, Si, SiGe, CGe, GeSn, SiGeSn, CSiGeSn and its combinations; and providing a p-type III-V semiconductor base layer made from a material selected from GaAs, AlGaAs, GaInAs, AlGaInAs, InP, GaP, GaInP, GaInPAs, AlInP, AlGaInP, InAs, InPAs, AlInAs, AlAs, GaSb, GaAsSb, InSb, GaInAsSb, GaInNAs, GaInNAsSb, GaN, AlN, InN, GaInN, AlGaN, AlInN, AlGaInN, and its combinations. It also involves providing a n-type emitter layer comprising a group-IV element selected from Ge, Si, SiGe, CGe, GeSn, SiGeSn, CSiGeSn, and its combinations; and providing a p-type group-IV semiconductor base layer selected from Ge, Si, SiGe, CGe, GeSn, SiGeSn, CSiGeSn, and its combinations; where the composition of the n-type emitter and p-type base layer differs. It involves providing a first layer comprising a solar cell emitter layer formed from a group-IV layer; and providing a second layer comprising tunnel junctions formed from at least one III-V semiconductor layers, the III-V semiconductor layers selected from GaAs, AlGaAs, GaInAs, AlGaInAs, InP, GaP, GaInP, GaInPAs, AlInP, AlGaInP, InAs, InPAs, AlInAs, AlAs, GaSb, GaAsSb, InSb, GaInAsSb, GaInNAs, GaInNAsSb, GaN, AlN, InN, GaInN, AlGaN, AlInN, AlGaInN, and its combinations. The method further involves providing a first layer comprising a solar cell emitter layer formed from a group-IV layer; and providing a second layer comprising tunnel junctions formed from at least one III-V semiconductor layers, the III-V semiconductor layers selected from p+GaAs/n+GaAs tunnel junctions; p+AlGaAs/n+GaAs tunnel junctions; p+GaAs/n+AlGaAs tunnel junctions; p+AlGaAs/n+AlGaAs tunnel junctions; p+AlGaAs/n+GaInP tunnel junctions; p+AlGaAs/n+AlGaInP tunnel junctions; and p+AlGaInP/n+AlGaInP tunnel junctions. The method further involves providing a solar cell emitter comprising a group-IV material, the emitter doped with an element selected from a column-III element and a column-V element. At least one column-IV element dopes one or more layers in a component of the cell selected from the solar cell base, the back-surface-field, the tunnel junction layers, or its combinations, and at least one region of the cell comprises at least one III-V semiconductor layer. The method involves providing a first layer comprising a solar cell emitter layer comprising a group-IV layer; and providing a second layer comprising a tunnel junction comprising at least one group-IV semiconductor layer selected from Ge, Si, SiGe, CGe, GeSn, SiGeSn, and CSiGeSn.