Rapid Thermal Processing for Front and Rear Contact Passivation

Presented at the 29th IEEE Photovoltaic Specialists Conference; New Orleans, Louisiana; May 17-24, 2002. ©2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Rapid firing processes are well known to allow improvements in solar cell contacts, particularly for the rear contact. Previous results characterizing the quality of a rear aluminum-alloyed back surface field have measured the effective surface recombination velocity, which depends not only on the material parameters of the back surface field, but also on the base doping. This paper shows that the determination of the recombination current density in the back surface field via photoconductance measurements is an accurate technique to measure the back surface field, independent of the base resistivity. Results show that fast firing conditions give the lowest recombination, but that the firing conditions can be altered substantially while still allowing high open circuit voltages