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.