Influence of Tabula Rasa on Process- and Light-Induced Degradation of Solar Cells Fabricated From Czochralski Silicon

Meyer, Abigail R.; LaSalvia, Vincenzo; Nemeth, William; Xu, Wanxing; Page, Matthew; Young, David L.; Agarwal, Sumit; Stradins, Paul

doi:10.1109/jphotov.2020.3020214

Title: Influence of Tabula Rasa on Process- and Light-Induced Degradation of Solar Cells Fabricated From Czochralski Silicon

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Abstract

Monocrystalline Si solar cells are fabricated from Czochralski (Cz) Si, which contains 10¹⁷–10¹⁸ cm^-3 oxygen atoms. Cz Si undergoes degradation during high-temperature thermal processing steps, such as dopant diffusion to form the p - n junction. This degradation in the bulk minority carrier lifetime can be related to the formation of oxygen precipitates. We found that a high-temperature annealing process known as tabula rasa (TR) not only mitigates process-induced degradation via oxygen precipitate nuclei dissolution, but also modifies subsequent light-induced degradation. We report on the bulk carrier lifetime of n - and p -type Cz Si after TR, which homogenizes the interstitial oxygen in the bulk Si to its monoatomic form in either an N 2 or O 2 environment. A control sample, which was not subjected to a TR processing step, experienced severe process-induced degradation during a boron emitter thermal budget as oxygen precipitates were formed in the Si bulk. These precipitates could be imaged using photoluminescence. Additionally, samples that underwent a TR processing step prior to the boron emitter thermal budget show efficient gettering of metallic impurities compared to the control sample, which showed a decline in the implied open-circuit voltage after the gettering step. Furthermore, modification ofmore »« less

Authors:

^[1]; LaSalvia, Vincenzo ^[2]; Nemeth, William ^[2];

^[3]; Page, Matthew ^[2];

^[2]; Agarwal, Sumit ^[3];

^[2]

National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Colorado School of Mines, Golden, CO (United States)

Publication Date:: Mon Sep 14 00:00:00 EDT 2020

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:: 1726057

Report Number(s):: NREL/JA-5900-77729
Journal ID: ISSN 2156-3381; MainId:30644;UUID:41f69b10-e381-4e6b-aa09-151e81c8c630;MainAdminID:18882

Grant/Contract Number:: AC36-08GO28308; EE0008171

Resource Type:: Accepted Manuscript

Journal Name:: IEEE Journal of Photovoltaics

Additional Journal Information:: Journal Volume: 10; Journal Issue: 6; Journal ID: ISSN 2156-3381

Publisher:: IEEE

Country of Publication:: United States

Language:: English

Subject:: 14 SOLAR ENERGY; degradation; oxygen precipitation; silicon solar cell; Tabula Rasa; photovoltaic

Citation Formats


                    Meyer, Abigail R., LaSalvia, Vincenzo, Nemeth, William, Xu, Wanxing, Page, Matthew, Young, David L., Agarwal, Sumit, and Stradins, Paul. Influence of Tabula Rasa on Process- and Light-Induced Degradation of Solar Cells Fabricated From Czochralski Silicon.  United States: N. p., 2020. 
Web.  doi:10.1109/jphotov.2020.3020214.

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                    Meyer, Abigail R., LaSalvia, Vincenzo, Nemeth, William, Xu, Wanxing, Page, Matthew, Young, David L., Agarwal, Sumit, & Stradins, Paul. Influence of Tabula Rasa on Process- and Light-Induced Degradation of Solar Cells Fabricated From Czochralski Silicon.  United States.  https://doi.org/10.1109/jphotov.2020.3020214

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                    Meyer, Abigail R., LaSalvia, Vincenzo, Nemeth, William, Xu, Wanxing, Page, Matthew, Young, David L., Agarwal, Sumit, and Stradins, Paul. Mon .  
"Influence of Tabula Rasa on Process- and Light-Induced Degradation of Solar Cells Fabricated From Czochralski Silicon".  United States.  https://doi.org/10.1109/jphotov.2020.3020214.  https://www.osti.gov/servlets/purl/1726057.

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@article{osti_1726057,

  title        = {Influence of Tabula Rasa on Process- and Light-Induced Degradation of Solar Cells Fabricated From Czochralski Silicon},

  author       = {Meyer, Abigail R. and LaSalvia, Vincenzo and Nemeth, William and Xu, Wanxing and Page, Matthew and Young, David L. and Agarwal, Sumit and Stradins, Paul},

  abstractNote = {Monocrystalline Si solar cells are fabricated from Czochralski (Cz) Si, which contains 1017–1018 cm-3 oxygen atoms. Cz Si undergoes degradation during high-temperature thermal processing steps, such as dopant diffusion to form the p - n junction. This degradation in the bulk minority carrier lifetime can be related to the formation of oxygen precipitates. We found that a high-temperature annealing process known as tabula rasa (TR) not only mitigates process-induced degradation via oxygen precipitate nuclei dissolution, but also modifies subsequent light-induced degradation. We report on the bulk carrier lifetime of n - and p -type Cz Si after TR, which homogenizes the interstitial oxygen in the bulk Si to its monoatomic form in either an N 2 or O 2 environment. A control sample, which was not subjected to a TR processing step, experienced severe process-induced degradation during a boron emitter thermal budget as oxygen precipitates were formed in the Si bulk. These precipitates could be imaged using photoluminescence. Additionally, samples that underwent a TR processing step prior to the boron emitter thermal budget show efficient gettering of metallic impurities compared to the control sample, which showed a decline in the implied open-circuit voltage after the gettering step. Furthermore, modification of the interstitial oxygen bonding by TR had a strong effect on the light-induced degradation kinetics. Instead of a typically observed monotonic decrease, minority carrier lifetime increases first, followed by a nonmonotonic decrease over a ~20 h period. Finally, we conclude that by modifying the interstitial oxygen bonding via TR pretreatment, p -type Cz Si wafers become substantially resistant to harsh solar cell processes and strongly modified light-induced degradation, which would open alternative ways to mitigate this degradation mechanism.},

  doi          = {10.1109/jphotov.2020.3020214},

  journal      = {IEEE Journal of Photovoltaics},

  number       = 6,

  volume       = 10,

  place        = {United States},

  year         = {Mon Sep 14 00:00:00 EDT 2020},

  month        = {Mon Sep 14 00:00:00 EDT 2020}

}

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