Gallium Contacts on p-type Silicon Substrates

Abstract

A significant reduction in contact resistance of palladium/silicon contacts was realised by the use of a thin intermediate gallium layer. The contact resistance of the palladium/gallium/silicon contact was found to be similar to aluminium/silicon contacts on 0·5 Ω cm silicon. Solar cells processed on 1 Ω cm substrates with this structure demonstrated better contact properties than conventional aluminium/silicon contacts. The improved characteristics are believed to be a result of gallium/silicon alloying at low temperature (400°C). The palladium layer is critical as aluminium/gallium/silicon layers show dramatically increased contact resistance. The palladium silicide may interact with the aluminium layer to form a stable ternary compound, preventing aluminium from penetrating deeper into the silicon. Show more