TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Component: The active silicon subcell comprises a p-n junction in silicon. The first subcell comprises a p-n junction in a first non- silicon semiconductor material. The second subcell comprises a p-n junction in a second non-silicon semiconductor material different from the first semiconductor material. A first bonded interface is located between the active silicon subcell and the first subcell. A second bonded interface is located between the active silicon subcell and the second subcell. The active silicon subcell comprises a silicon wafer containing a p-n junction. A third non-silicon subcell comprises a p-n junction in a third non-silicon semiconductor material different from the first and second semiconductor materials. It electrically contacts the second non-silicon subcell. A first side of the second non-silicon subcell is bonded to the second side of the active silicon subcell. The third non-silicon subcell is epitaxially grown on a second side of the second non-silicon subcell. The third semiconductor material comprises a first band gap. The second semiconductor material comprises a second band gap that is narrower than the first band gap but wider than a band gap of silicon. The third semiconductor material comprises a band gap narrower than the band gap of silicon. A first non-silicon single crystal layer of the first non- silicon subcell is bonded to a single crystal silicon substrate which is part of the silicon subcell. The first layer is not lattice matched to the silicon substrate. It is transferred from a single crystal bulk non-silicon substrate. It has a single crystal structure quality within an order of magnitude from that of the single crystal bulk non-silicon substrate. An abrupt bonded interface is present between the first layer and the silicon substrate so that a metamorphic layer is not located between the first layer and the silicon substrate. A conductive bond is present between the first layer and the silicon substrate. A first highly doped tunnel junction is located between the first non-silicon subcell and the active silicon subcell. A second highly doped tunnel junction is located between the second non-silicon subcell and the active silicon subcell. An interface between the first non-silicon subcell and the silicon subcell is electrically insulating. The first non-silicon subcell and the silicon subcell are electrically connected in parallel. The solar cell comprises a gallium arsenide or germanium template layer, a gallium arsenide subcell epitaxially grown on a first side of the template layer, an aluminum indium gallium phosphide subcell formed on the subcell and bonded to the cover glass, an indium phosphide template layer having a first side bonded to a second side of the template layer, and an indium gallium arsenide subcell epitaxially grown on a second side of the template layer.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The first semiconductor material comprises indium gallium arsenide or germanium. The second semiconductor material comprises gallium arsenide. The third semiconductor material comprises AlxInyGa1- x-yP, where one but not both of x or y may equal to zero.