Excellent Passivation of n‐Type Silicon Surfaces Enabled by Pulsed‐Flow Plasma‐Enhanced Chemical Vapor Deposition of Phosphorus Oxide Capped by Aluminum Oxide

Phosphorus oxide (PO x ) capped by aluminum oxide (Al 2 O 3 ), prepared by atomic layer deposition (ALD), has recently been introduced as a surface passivation scheme for planar n ‐type FZ silicon. In this work, a fast pulsed‐flow plasma‐enhanced chemical vapor deposition (PECVD) process for the PO x layer is introduced, making it possible to increase the PO x deposition rate significantly while maintaining the PO x /Al 2 O 3 passivation quality. An excellent surface passivation is realized on n ‐type planar FZ and Cz substrates ( J 0 = 3.0 fA cm −2 ). Furthermore, it is demonstrated that the PO x /Al 2 O 3 stack can passivate textured surfaces and that the application of an additional PECVD SiN x capping layer renders the stack stable to a firing treatment that is typically used in fire‐through contact formation ( J 0 = 12 fA cm −2 ). The excellent surface passivation is enabled by a high positive fixed charge density ( Q f ≈ 4 × 10 12 cm −2 ) and an ultralow interface defect density ( D it ≈ 5 × 10 10 eV −1 cm −2 ). Finally, outstanding passivation is demonstrated on textured silicon with a heavy n + surface doping, as is used in solar cells, on par with alnealed SiO 2 . These findings indicate that PO x /Al 2 O 3 is a highly suited passivation scheme for n ‐type silicon surfaces in typical industrial solar cells.