Contact Resistivity of Evaporated Al Contacts for Silicon Solar Cells

The contact resistivity of evaporated Al on doped silicon is examined for a range of process conditions common to the fabrication of laboratory silicon solar cells. The effects of silicon surface preparation prior to evaporation, sintering temperature, the use of a shutter, and evaporation power are investigated. The presented evaporation conditions yielded the lowest published contact resistivity between Al- and phosphorus-doped Si over a large range of doping concentration. It is also demonstrated that a contact resistivity below 10^-6 Ω·cm² can be achieved without sintering. Three-dimensional simulations are utilized to compare the obtained results for evaporated Al contacts with those for passivated contacts.