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The Passivation Characteristics of Poly-Si/SiOx Stack for High-Efficiency Silicon Solar Cells

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Abstract

The Poly-Si/SiOx stack passivation structure incorporate doped polycrystalline silicon (Poly-Si) and tunneling silicon oxide (SiOx) thin films allows for majority-carrier transport as well as block minority carriers and suppress recombination, and thus enable very high efficiency. Up to now the Poly-Si/SiOx stack passivation have been a widespread research topic for photovoltaic researchers, but most of the works are only focused on n-type doped structures and the rear side polished surface of the solar cells. In order to apply the Poly-Si/SiOx stack structure to the front textured surface and p+ emitter region to obtain high-efficiency double-sided passivated contact solar cells and Si-based tandem cells in the future. In this work, passivation properties of Poly-Si/SiOx stack capped with SiNx:H layer are discussed based on different crystalline silicon surface morphologies, dopant types, doping profiles and thickness of Poly-Si layer. With proper doping process control, an excellent implied open-circuit voltage (iVoc) of 706 mV with a saturation current density (J0) value of 12 fA/cm2 has been obtained for the boron-doped Poly-Si/SiOx stack capped with SiNx:H based on the textured surface, and an iVoc of 736 mV with a J0 value of 2 fA/cm2 has been acquired for the phosphorus-doped Poly-Si/SiOx stack capped with SiNx:H based on the acid polished surface. The results show that the polished surface and thinner Poly-Si layer are helpful for passivation. For the doped Poly-Si/SiOx stack structure, the doping source will penetrate the tunneling SiOx layer into the silicon bulk to form a certain penetration depth on the surface of the silicon substrate. In order to acquire the high iVoc (low J0) value, a penetration depth of around 160 nm is needed to the phosphorus-doped Poly-Si/SiOx stack, while a penetration depth of less than 25 nm is required for boron-doped Poly-Si/SiOx stack. In addition, there is a linear relationship between the Rsheet value and the reciprocal value of the Poly-Si (n+) layer thickness.

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Acknowledgements

This work is funded by the China State Power Investment Corporation Limited (SPIC).

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Authors and Affiliations

  1. QingHai Huanghe Hydropower Development Co., Ltd. Xi’an Solar Power Branch, 589 East Chang’an Avenue, Chang’an District, Xi’an, 710100, China

    Tianjie Zhang, Xiaoyong Qu, Yonggang Guo, Dawei Liu, Xiang Wu & Jiaqing Gao

  2. College of Automation and Information Engineering, Xi’an University of Technology, Xi’an, 710048, China

    Tao Lin

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  1. Tianjie Zhang
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  2. Xiaoyong Qu
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  3. Yonggang Guo
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  4. Dawei Liu
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  5. Xiang Wu
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  6. Jiaqing Gao
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  7. Tao Lin
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Contributions

All authors contribute to the study conception and design. As the major contributors in writing the manuscript, Tianjie Zhang and Xiaoyong Qu complete the design and implementation of the experimental scheme. Material preparation, data collection and analysis are performed by Yonggang Guo, Dawei Liu, Xiang Wu, Jiaqing Gao and Tao Lin. The first draft of the manuscript is written by Tianjie Zhang and all authors comment on previous versions of the manuscript. All authors read and agree to the published version of the manuscript.

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Correspondence to Tianjie Zhang.

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Zhang, T., Qu, X., Guo, Y. et al. The Passivation Characteristics of Poly-Si/SiOx Stack for High-Efficiency Silicon Solar Cells. Silicon 15, 1659–1668 (2023). https://doi.org/10.1007/s12633-022-02127-2

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