Poly-SiO&lt;sub&gt;x&lt;/sub&gt; Passivating Contacts with Plasma-Assisted N&lt;sub&gt;2&lt;/sub&gt;O Oxidation of Silicon (PANO-SiO&lt;sub&gt;x&lt;/sub&gt;)

Yao, Z.; Yang, G.; Han, C.; Procel Moya, P.A.; Özkol, E.; Yan, J.; Zhao, Y.; Cao, L.; van Swaaij, R.A.C.M.M.; Mazzarella, L.; Isabella, O.

doi:10.1002/solr.202300186

Poly-SiO_x Passivating Contacts with Plasma-Assisted N₂O Oxidation of Silicon (PANO-SiO_x)

Title

Poly-SiO_x Passivating Contacts with Plasma-Assisted N₂O Oxidation of Silicon (PANO-SiO_x)

Author

Yao, Z. (TU Delft Photovoltaic Materials and Devices)
Yang, G. (TU Delft Photovoltaic Materials and Devices)
Han, C. (TU Delft Photovoltaic Materials and Devices; Sun Yat-sen University)
Procel Moya, P.A. (TU Delft Photovoltaic Materials and Devices)
Özkol, E. (TU Delft Photovoltaic Materials and Devices)
Yan, J. (TU Delft Photovoltaic Materials and Devices)
Zhao, Y. (TU Delft Photovoltaic Materials and Devices)
Cao, L. (TU Delft Photovoltaic Materials and Devices)
van Swaaij, R.A.C.M.M. (TU Delft Photovoltaic Materials and Devices)
Mazzarella, L. (TU Delft Photovoltaic Materials and Devices)
Isabella, O. (TU Delft Photovoltaic Materials and Devices)

Date

2023

Abstract

Passivating contacts are crucial for realizing high-performance crystalline silicon solar cells. Herein, contact formation by plasma-enhanced chemical vapor deposition (PECVD) followed by an annealing step is focused on. Poly-SiO_x passivating contacts by combining plasma-assisted N₂O-based oxidation of silicon (PANO-SiO_x) with a thin film of phosphorus (n⁺) or boron (p⁺)-doped hydrogenated amorphous silicon oxide (a-SiO_x:H) are manufactured. Postannealing is conducted for transitioning a-SiO_x:H into poly-SiO_x. The aim is to achieve a contact with low absorption and high-quality passivation. It is demonstrated that by tuning the plasma oxidation process time and power, the PANO-SiO_x thickness and its passivation quality can be controlled. A higher SiO₂ content is observed in PANO-SiO_x than in the nitric acid oxidation of silicon (NAOS-SiO_x) counterpart. PANO-SiO_x acts as a stronger diffusion barrier for both boron and phosphorus atoms compared to NAOS-SiO_x, affecting the dopant distribution during annealing. Implied open-circuit voltages up to 751 and 710 mV for n⁺ and p⁺ flat symmetric samples, respectively, are demonstrated. With respect to standard thermally grown SiO₂ tunneling oxide combined with (in/ex)situ-doped low-pressure chemical vapor deposition poly-Si, this study presents a simple alternative for manufacturing passivating contact fully based on PECVD processes.