Ultra thin Al2O3 passivation for hetero-junction Si solar cell

• Published in: 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) pp. 2684 - 2687
• Main Authors: Kim, Sangpyeong, Balaji, Pradeep, Augusto, Andre, Bowden, Stuart, Honsberg, Christiana B.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.06.2019
• Subjects: Al 2 O 3 passivation; hetero-junction; silicon solar cell; ultra thin Al 2 O 3
• DOI: 10.1109/PVSC40753.2019.8980907

This work focuses on ultra thin (≤ 1nm) Al 2 O 3 passivation for silicon hetero-junction solar cell. We developed a post annealing process compatible with the hetero-junction structure. We accomplished effective minority lifetime over 3 ms and implied open circuit voltages over 700 mV using a 10 nm thick Al 2 O 3 . To promote carrier transportation across the Al 2 O 3 layer we had to reduce the layer thickness by a factor of 10. The 1 nm thin layer alone provides very poor passivation as demonstrated by the low effective minority carrier lifetime (50μs) and low implied open circuit (590mV). To improve both passivation and carrier transportation, a ultra thin stack of SiO 2 -Al 2 O 3 (1.7 nm/1 nm) was developed successfully and effective minority carrier lifetimes up to 350 μs and implied open circuit voltage up to 648mV were demonstrated without post annealing optimization.