Passivation Enhancement of Poly-Si Carrier-Selective Contacts by Applying ALD Al_2O_3 Capping Layers

Passivation Enhancement of Poly-Si Carrier-Selective Contacts by Applying ALD Al_2O_3 Capping Layers

Yang, G. (TU Delft Photovoltaic Materials and Devices)
Van de Loo, Bas (SoLayTec)
Stodolny, Maciej (New Energies Research and Technology, Tha Hague)
Limodio, G. (TU Delft Photovoltaic Materials and Devices)
Melskens, Jimmy (TNO Energy Transition)
Isabella, O. (TU Delft Photovoltaic Materials and Devices)
Weeber, A.W. (TNO Energy Transition)
Zeman, M. (TU Delft Electrical Sustainable Energy)
Kessels, W. M.M. (Eindhoven University of Technology)

Electrical Sustainable Energy

2021

Hydrogenation of polycrystalline silicon (poly-Si) passivating contacts is crucial for maximizing their passivation performance. This work presents the application of Al2O3 prepared by atomic layer deposition as a hydrogenating capping layer. Several important questions related to this application of Al2O3 are addressed by comparing results from Al2O3 single layers, SiNx single layers, and Al2O3/SiNx double layers to different poly-Si types. We investigate the effect of the Al2O3 thickness, the poly-Si thickness, the poly-Si doping type, and the postdeposition annealing treatment on the passivation quality of poly-Si passivating contacts. Especially, the Al2O3/SiNx stack greatly enhances the passivation quality of both n+ and p+ doped as well as intrinsic poly-Si layers. The Al2O3 layer thickness is crucial for the single-layer approach, whereas the Al2O3/SiNx stack is less sensitive to the thickness of the Al2O3 layer. A thicker Al2O3 layer is needed for effectively hydrogenating p+ compared to n+ poly-Si passivating contact. The capping layers can hydrogenate poly-Si layers with thicknesses up to at least 600 nm. The hydrogenation-enhanced passivation for n+ poly-Si is found to be more thermally stable in comparison to p+ poly-Si. These results provide guidelines on the use of Al2O3 capping layers for poly-Si contacts to significantly improve their passivation performance.

Atomic layer deposition (ALD) Al2O3
hydrogenation
passivation quality
polycrystalline silicon (poly-Si) passivating contacts
thermal stability

http://resolver.tudelft.nl/uuid:e1b28dfa-307d-4500-a878-476c2ec293fd

https://doi.org/10.1109/JPHOTOV.2021.3119595

2156-3381

IEEE Journal of Photovoltaics, 12 (1), 259-266

Institutional Repository

journal article

© 2021 G. Yang, Bas Van de Loo, Maciej Stodolny, G. Limodio, Jimmy Melskens, O. Isabella, A.W. Weeber, M. Zeman, W. M.M. Kessels, More Authors