Cobalt disilicide intercell ohmic contacts for multijunction photovoltaic energy converters

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Abstract
We have created thin buried films of low resistivity CoSi2 in silicon by ion implantation, and used them to provide intercell ohmic contacts for monolithically stacked multijunction photovoltaic energy converters. We have grown epitaxial silicon pn junction diodes by chemical vapor deposition onto the thin film of crystalline silicon formed over the CoSi2 layer after post‐implantation annealing. A single junction photovoltaic device with two CoSi2 contacts displayed an open circuit voltage of 0.60 V and a fill factor of 0.80, while a double junction tandem cell with three CoSi2 interconnects generated 1.2 V, under identical conditions of illumination with a Nd:YAG laser. These results indicate very low defect levels in the deposited silicon epitaxial layers, and excellent functioning of the CoSi2 interconnects.