Ultrafast lifetime regeneration of boron-doped Czochralski-silicon in an industrial belt-line furnace

摘要

Solar cells made of boron-doped, oxygen-rich Czochralski-grown silicon (Cz-Si) wafers suffer degraded efficiency when illuminated, an effect sometimes labelled light-induced degradation (LID). This is caused by a specific defect centre within the silicon bulk, often referred to as a BO defect, which activates its recombination properties under illumination, leading to a degradation in carrier lifetime. However, the BO defect centre can be permanently deactivated, and the lifetime permanently recovered, by illumination at an elevated temperature. In this paper the focus is on transferring ISFH's lab-type BO deactivation process to an ultrafast high-throughput process, employing an industrial-type belt furnace especially designed by centrotherm photovoltaics AG for this very purpose. By using this industrial furnace, inline regeneration in a solar cell production line becomes feasible. The investigations clearly demonstrate that the industrial belt furnace is well suited to permanently deactivating the BO complex; in addition, excellent stability of the lifetimes after regeneration is demonstrated.