The passivation of p(+) Si surfaces is challenging due to the fact that most passivation films have an intrinsically high positive fixed charge. In this work we show experimentally that low-temperature plasma-enhanced chemical vapor deposited SiOx/SiNy stacks with a low positive fixed charge density (+10(11) cm(-2)) and very low interface defect density (similar to 3 x 10(10) eV(-1) cm(-2)) as measured by contactless corona-voltage measurements can effectively passivate p(+) surfaces resulting in emitter saturation current density (J(oe)) values of 25 and 45 fA/cm(2) on planar and textured 75 Omega/sq p(+) silicon after industrial firing with a set-temperature of similar to 800 degrees C, respectively. Based on contactless corona-voltage measurements and advanced device simulations, we explain the mechanism of surface passivation by PECVD SiOx/SiNy dielectric stack to be completely dominated by chemical passivation rather than field-effect passivation. Furthermore, from advanced device simulations we illustrate the role of fixed charge in surface passivation and in the extraction of fundamental surface recombination velocity parameter for p(+) silicon surfaces. The fundamental surface recombination velocity parameter for electrons is determined to be about 400 cm/s at these c-Si/SiOx interfaces. With excellent optical and passivation properties, SiOx/SiNy dielectric stacks are suitable for high-efficiency and cost-effective industrial n-type silicon wafer solar cells. (C) 2013 Elsevier B.V. All rights reserved.