TY - GEN
T1 - Quantitative Understanding and Implementation of Screen Printed p+ Poly-Si/Oxide Passivated Contact to Enhance the Efficiency of p-PERC Cells
AU - Choi, Wook Jin
AU - Jain, Aditi
AU - Huang, Ying Yuan
AU - Ok, Young Woo
AU - Rohatgi, Ajeet
N1 - Publisher Copyright:
© 2020 IEEE.
PY - 2020/6/14
Y1 - 2020/6/14
N2 - This paper reports on the modeling, optimization, and implementation of p-TOPCon (tunnel oxide passivating contacts) on the rear side of a PERC to enhance its cell efficiency. Local Al-BSF of a traditional PERC was replaced by p+ poly-Si/oxide passivated contact composed of 15Å thick chemically grown tunnel oxide, capped with 120-250nm thick p+ poly-Si layer grown by LPCVD. Process optimization resulted in full-area un-metallized recombination current density (J0b, pass) of < 5fA/cm2 for planar surface, nearly independent of poly-Si thickness in this range. Metallized Jo showed an increase with decreased poly-Si thickness and was found to be 9.6 and 25fA/cm2 for 250nm and 120nm poly-Si respectively, with 4.6% direct metal-Si contact fraction, suitable for bifacial cells. A 21.4% baseline PERC cell with local BSF was fabricated and characterized to extract the rear side recombination current density (J0b,) of 65fA/cm2. Detailed analysis and device simulation showed that by replacing this LBSF with 250nm TOPCon developed in the study should produce a Voc enhancement of 9.2mV, consistent with the observed cell Voc increase of 10mV.
AB - This paper reports on the modeling, optimization, and implementation of p-TOPCon (tunnel oxide passivating contacts) on the rear side of a PERC to enhance its cell efficiency. Local Al-BSF of a traditional PERC was replaced by p+ poly-Si/oxide passivated contact composed of 15Å thick chemically grown tunnel oxide, capped with 120-250nm thick p+ poly-Si layer grown by LPCVD. Process optimization resulted in full-area un-metallized recombination current density (J0b, pass) of < 5fA/cm2 for planar surface, nearly independent of poly-Si thickness in this range. Metallized Jo showed an increase with decreased poly-Si thickness and was found to be 9.6 and 25fA/cm2 for 250nm and 120nm poly-Si respectively, with 4.6% direct metal-Si contact fraction, suitable for bifacial cells. A 21.4% baseline PERC cell with local BSF was fabricated and characterized to extract the rear side recombination current density (J0b,) of 65fA/cm2. Detailed analysis and device simulation showed that by replacing this LBSF with 250nm TOPCon developed in the study should produce a Voc enhancement of 9.2mV, consistent with the observed cell Voc increase of 10mV.
UR - http://www.scopus.com/inward/record.url?scp=85099544603&partnerID=8YFLogxK
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U2 - 10.1109/PVSC45281.2020.9300878
DO - 10.1109/PVSC45281.2020.9300878
M3 - Conference contribution
AN - SCOPUS:85099544603
T3 - Conference Record of the IEEE Photovoltaic Specialists Conference
SP - 821
EP - 824
BT - 2020 47th IEEE Photovoltaic Specialists Conference, PVSC 2020
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 47th IEEE Photovoltaic Specialists Conference, PVSC 2020
Y2 - 15 June 2020 through 21 August 2020
ER -