Hole-selective SiNx and AlOx tunnel nanolayers for improved polysilicon passivating contacts

Journal article

A highly efficient hole-selective passivating contact remains the crucial step required to increase the efficiency of polysilicon-based Si solar cells. The future development of solar modules depends on a device structure that can complement the electron-selective Tunnel Oxide Passivating Contact (TOPCon) with an equivalent hole-selective contact. We investigate Plasma Enhanced Chemical Vapour Deposited (PECVD) SiNx and Atomic Layer Deposited (ALD) AlOx as alternative nanolayers for the passivation layer in polysilicon tunnel contacts. We have fabricated p+ poly-Si contacts with resistivities below 100 mΩ⋅cm2 using these alternative metal oxide and nitride nanolayers. Initial passivation tests yielded low levels of passivation; however, a detailed understanding of the nanolayers elucidated the strategies to improve passivation significantly, achieving an implied open circuit voltage (iVOC) of 698 mV and dark saturation current density (J0) of 34 fA/cm2 for a p+ poly-Si contact using a PECVD SiNx interlayer. These are among the best reported for nitride-based nanolayer tunnelling contacts, with research into nitride-based tunnelling contacts being still in its infancy.

Authors: McNab, S; Morisset, A; Libraro, S; Genç, E; Niu, X

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: ACS Applied Energy Materials
• Volume: 7
• Issue: 22
• Pages: 10259-10270
• Place of publication: United States
• Publication date: 2024-11-14
• Acceptance date: 2024-11-06
• DOI: 10.1021/acsaem.4c01170
• EISSN: 2574-0962
• Pmid: 39611134
• Language: English
• Keywords: hole-selective contacts; silicon solar cells; polysilicon contacts; silicon nitride; aluminum oxide; conduction mechanisms; passivation