Patent ID: 7863516

Claim:
A monolithic, multijunction, semiconductor photovoltaic solar cell comprising: an electrically conductive substrate selected from the group consisting of an electrically conductive Ge substrate and an electrically conductive GaAs substrate; a first subcell including Ge, an effective bandgap energy of the first subcell being about 0.7 ev; a second subcell including a plurality of epitaxially-grown semiconductor layers that include layers with self-assembled InGaAs quantum dots, the layers with the self-assembled InGaAs quantum dots being intercalated with GaAs, AlGaAs, or GaPAs layers, an effective bandgap energy of the second subcell being about 1.16 eV; and a third subcell including GalnP, AlGaAs or AlGalnP, the effective bandgap energy of the third subcell being about 1.8 eV, the first, second, and third subcells being disposed in series and each having a p-n or p-i-n junction formed therein, the first, second, and third subcells being disposed on the electrically conductive substrate with first subcell being disposed closest to the electrically conductive substrate, the third subcell being the farthest from the electrically conductive substrate, and the second subcell being disposed between the first subcell and the second subcell.