INVESTIGATION ON THERMAL OXIDE THICKNESS FOR PASSIVATION OF N-TYPE BIFACIAL SOLAR CELL APPLICATION

摘要

For n-type silicon bifacial cells with boron emitter, thermal oxide is a viable option for passivation. In this study, we compared the performance of thermal oxide passivation with different oxide thicknesses. We fabricated symmetrical p+/n/p+ and n+/n/n+ structures to extract J_(0e) and carrier lifetime. With 10nm oxide on boron emitter, the emitter saturation current density (J_(0e)) was 200 fA/cm~2. Reducing the thickness decreased J_(0e) to 120 fA/cm~2. We also obtained the implied open circuit voltage (V_(oc)), V_(oc) limit, and real Voc of cells passivated by 5nm and 10nm SiO_2. The external quantum efficiency (EQE) data showed slightly enhanced short wavelength response for the 5nm case. The study enhanced our understanding about how to optimize passivation for boron emitter, paving a way to achieve high efficiency n-type solar cells.