Doping, Passivation and Photovoltaic Properties of Ultra-Thin Poly-Silicon

Abstract

Abstract: The doping process, passivation and photovoltaic properties of 70 nm ultra-thin poly-silicon were studied in this paper. The optimal doping process for 70 nm ultra-thin poly-silicon was identified, the results show that when the ion implantation dose is 3.2×10¹⁵ cm^-3 and annealed at 855 ℃ for 20 min, the passivation properties of 70 nm ultra-thin poly-silicon is comparable to that of conventional 120 nm poly-silicon, and the surface doping concentration value of 5.6×10²⁰ atoms/cm³ for 70 nm ultra-thin poly-silicon is achieved, which is much higher than that of 120 nm doped poly-silicon (2.5×10²⁰ atoms/cm³). Based on the characteristic of reduced thickness and heavy doping for 70 nm ultra-thin poly-silicon, the conversion efficiency of TOPCon solar cells processed on large area (6 inch) Cz wafers significantly improves due to the low parasitic absorption and excellent filed passivation effect. The I_sc is increased by 20 mA and 0.3% improvement of FF, leading to an absolute efficiency gain of 0.13% for the champion conversion efficiency, as well as low series resistance.

Key words: TOPCon solar cell, poly-silicon, doping, ion implantation, passivation contact, parasitic absorption, photoelectric conversion efficiency

CLC Number:

TM914.4

SONG Zhicheng, YANG Lu, ZHANG Chunfu, LIU Dawei, NI Yufeng, ZHANG Ting, WEI Kaifeng. Doping, Passivation and Photovoltaic Properties of Ultra-Thin Poly-Silicon[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2022, 51(3): 434-440.

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