Auger-limited bulk lifetimes in industrial Czochralski-grown n-type silicon ingots with melt recharging

This study reports on the electronic properties of industrial phosphorus-doped n-type silicon ingots for photovoltaic applications grown using the Recharged Czochralski method. The electronic quality is assessed via carrier lifetime measurements, both directly on the ingots and on passivated wafers, and via implied open-circuit ( i V O C ), and implied maximum power point ( i V M P P ) voltages. The wafers are studied in the as-grown state, and after various high temperature steps, including Tabula Rasa , phosphorus diffusion gettering, and boron diffusion. The material exhibited very high bulk quality, with bulk lifetimes up to 8 ms at an injection level of 5 × 10 14 cm − 3 , and with i V O C (1-sun) values up to 750 mV , prior to any high temperature processing. A Tabula Rasa step did not significantly improve the wafer quality, indicating a low presence of oxygen-related defects in this material, consistent with the low interstitial oxygen content of below 5 × 10 17 cm − 3 . However, phosphorus diffusion gettering improved the wafer quality, especially towards the tail end of each ingot, and at lower injection levels near maximum power point. Phosphorus diffusion gettering increased the i V O C (1-sun) of the wafers by around 5 mV , approaching the Auger limit. Additionally, a boron diffusion step had minimal impact on the bulk lifetimes. Overall, our findings suggest that these RCz-grown n-type wafers exhibit very high quality, approaching the Auger limit near open-circuit, and are well-suited for high-efficiency solar cells without the need for additional high-temperature processing. • Assessing the material quality of n-type RCz industrial ingots, both directly on the ingot and on passivated wafers. • Bulk lifetimes of up to 8 ms and i V O C (1-sun) values up to 750 mV . • Low interstitial oxygen content of below 5 × 10 17 cm − 3 , low presence of oxygen-related defects. • Improvement of the wafer quality after gettering, particularly towards the bottom of each ingot, nearing the Auger limit. • No significant degradation after boron diffusion.