Aluminum alloy back p-n junction dendritic web silicon solar cell

A new silicon solar cell structure is presented in which the p-n junction i s formed by alloying aluminum with n-type silicon, and where this p-n junct ion is located at the back (unilluminated) side of the cell. With a phospho rus front diffusion, the resultant n(+) np(+) structure has been implemente d using dendritic web silicon substrates which are 100 mum thick and doped with antimony to 20 Omega cm. Such a structure eliminates shunting of the p -fi junction, provides an effective front surface field, enables a high min ority carrier lifetime in the base, and is immune to light-induced degradat ion. Using only production-worthy, high-throughput processes, aluminum allo y back junction dendritic web cells have been fabricated with efficiencies up to 14.2% and with corresponding minority carrier (hole) lifetime in the base of 115 mus. (C) 2001 Elsevier Science B.V. All rights reserved.