A new method for bulk passivation in multicrystalline-Si by sulfur

A new bulk passivation method for multicrystalline-Si using H₂S is proposed. It has the added benefit of both hydrogen and sulfur for bulk passivation. Minority carrier lifetime of the samples is measured to monitor the effect of passivation. It is found that sulfur passivation takes place at higher temperatures, ~100°C higher, than hydrogen passivation, and sulfur passivation results in much higher lifetime gains than hydrogen passivation (2750% vs. 359%). Post-annealing in ambient further improves the lifetime of the samples, which is attributed to improved surface passivation on the p-type samples by Al₂O₃. The highest lifetime gain achieved is 6750% for H₂S passivated samples vs. ~2400% for forming gas passivated samples. Post-annealing also improves the stability of the increased lifetime.