Abstract: A thin-film solar cell is made up of semiconductor layers formed on an aluminum silicon eutectic alloy substrate. The substrate includes an aluminum oxide insulator containing electrically conducting silicon nucleation sites which is interposed between the electrical contact of the substrate and the adjacent semiconductor. Grain boundaries and voids terminate on the insulator. The solar cell is fabricated by oxidizing the aluminum-silicon substrate to form a layer of aluminum oxide with unactivated silicon site material dispersed therein and activating the silicon nucleation sites during growth of the semiconductor layers.

Abstract: A thin-film solar cell on a substrate is fabricated by selectively introducing nucleation sites into the insulator layer which is formed on the substrate material, and activating the nucleation sites during growth of the semiconductor layers. The solar cell is made up of semiconductor layers formed on a substrate. The substrate includes an insulator containing electrically conducting nucleation sites which is interposed between the electrical contact of the substrate and the adjacent semiconductor. The insulator can also be optically transparent. Grain boundaries and voids terminate on the insulator.

Abstract: A thin-film solar cell is made up of semiconductor layers formed on a substrate. The substrate includes an insulator containing electrically conducting nucleation sites which is interposed between the electrical contact of the substrate and the adjacent semiconductor. The insulator can also be optically transparent. Grain boundaries and voids terminate on the insulator. The solar cell is fabricated by selectively introducing nucleation sites into the insulator layer which is formed on the substrate material, and activating the nucleation sites during growth of the semiconductor layers.

Abstract: An improved tandem solar cell includes a gallium arsenide phosphide top solar cell and silicon bottom solar cell. The gallium arsenide phosphide solar cell is fabricated on a transparent gallium phosphide substrate and either placed in series with the silicon solar cell for a two terminal device or wired separately for a four terminal device. The top solar cell should have an energy gap between 1.77 and 2.09 eV for optimum energy conversion efficiency. A compositionally graded transition layer between the gallium phosphide substrate and the active semiconductor layers reduces dislocations in the active region. A gallium phosphide cap layer over the gallium arsenide phosphide solar cell reduces surface recombination losses.