RTP-processed 17.5 % efficient silicon solar cells featuring a record small thermal budget

This paper presents the development and analysis of 17.5 % efficient silicon solar cells on 0.9 omega cm PV-grade Cz-Si, featuring a record small thermal budget. The cells have been processed by rapid thermal processing (RTP) using high heating and cooling rates of 100 K/s. The involved processes consist of a 5 s RTP step at 930 °C for the simultaneous formation of phosphorus emitter and aluminium back surface field and a 30 s rapid thermal oxidation (RTO) at 950 °C for emitter passivation. Detailed analysis reveals that the emitter saturation current is reduced by a factor of 3-4 due to RTO passivation in spite of high carrier surface concentration of 4x10(exp 20) cm-3. Current cell efficiencies are limited by poor quality of the Al-BSF as PC-lD simulations show.