Investigation of Copper Plated Contacts for Silicon Solar Cells

As an alternative method to printing techniques, the metal contacts of silicon solar cells can be realized by plating. Copper is an interesting choice of metal, especially taking into account its high conductivity and low price. However, barrier layers are needed to prevent copper diffusion into the silicon. In this paper we use TXRF, QSSPC and CDI to evaluate the potential diffusion of copper through the silicon nitride anti reflection coating after exposing the wafers to Cu plating solutions. Three plating solutions with varying purity are investigated. Furthermore first PERC solar cells have been realized with copper plated contacts having a Ti/Cu contact layer with a best large area cell efficiency of 18.3%.