Ultrathin silicon oxide prepared by in-line plasma-assisted N₂O oxidation (PANO) and the application for n-type polysilicon passivated contact

Journal Article · 02 January 2020 · Solar Energy Materials and Solar Cells

DOI: https://doi.org/10.1016/j.solmat.2019.110389 · OSTI ID:1592396

Huang, Yuqing ^[1]; Liao, Mingdun ^[1]; Wang, Zhixue ^[2]; Guo, Xueqi ^[1]; Jiang, Chunsheng ^[3]; Yang, Qing ^[1]; Yuan, Zhizhong ^[4]; Huang, Dandan ^[1]; Yang, Jie ^[5]; Zhang, Xinyu ^[5]; Wang, Qi ^[5]; Jin, Hao ^[5]; Al-Jassim, Mowafak ^[3]; Shou, Chunhui ^[6]; Zeng, Yuheng ^[1]; Yan, Baojie ^[1]; Ye, Jichun ^[1]

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1. Chinese Academy of Sciences (CAS), Ningbo City (China). Ningbo Materials Inst. of Technology and Engineering
2. Chinese Academy of Sciences (CAS), Ningbo City (China). Ningbo Materials Inst. of Technology and Engineering; Jiangsu Univ., Zhenjiang City (China). School of Material Science & Engineering
3. National Renewable Energy Lab. (NREL), Golden, CO (United States)
4. Jiangsu Univ., Zhenjiang City (China). School of Material Science & Engineering
5. Zhejiang Jinko Solar Co. Ltd, Haining City (China)
6. Zhejiang Energy Group R&D, Hangzhou (China)

We develop a plasma-assisted nitrous-oxide (N₂O) gas oxidation (PANO) method to prepare the ultrathin silicon oxide (SiO_x) for polysilicon (poly-Si) passivated contact. The effects of preparation conditions, including the substrate temperature, processing time, and plasma power, are studied. Afterwards, we integrate the PANO SiO_x into the polysilicon passivated contact and optimize the passivation and contact performances. Excellent surface passivation with the n-type poly-Si and PANO SiO_x on the n-type c-Si wafer is achieved by 880 °C annealing, which shows competitive passivation quality to the one with NASO SiO_x. Champion implied open-circuit voltage (iV_oc) and single-sided recombination saturated current (J₀) reach 730 mV and 4.3 fA/cm² after crystallization; and they are further improved to 747 mV and 2.0 fA/cm² (3 × 10¹⁵cm_-3) after subsequent AlO_x/SiN_x hydrogenation. Using transmission electron microscopy (TEM), we find that the thickness of PANO SiO_x ranges 1.1–2.4 nm and the controlled nitric acid oxidized SiO_x (NAOS) ranges 1.3–1.8 nm. The contact resistivity (ρ_c) is typically <10 mΩ cm² with the annealing temperature of >820 °C. Also, the crystallinity, phosphorous in-diffusion profile, and current-leaking density of the passivated contacts are investigated. In general, the PANO SiO_x and in-situ doping amorphous silicon precursor can be fabricated in one PECVD system without additional equipment or transfer procedures, which is favorable for the high-efficiency, low-cost industrial manufacture.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1592396
• Report Number(s): NREL/JA-5K00-75830
• Journal Information: Solar Energy Materials and Solar Cells, Vol. 208, Issue C; ISSN 0927-0248
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English