Laades, A.; Sperlich, H.-P.; Stürzebecher, U.; Angermann, H.; Töfflinger, J.; John, W.; Blech, M.; Bähr, M.; Lawerenz, A.: INTERFACE ISSUES OF ALL-PECVD SYNTHESIZED ALOX/SINX PASSIVATION STACKS FOR SILICON SOLAR CELLS. In: Nowak, S. [Ed.] : 27th European Photovoltaic Solar Energy Conference and Exhibition ; Frankfurt, Main: EU PVSEC ; 24.9.2012-28.9.2012München: WIP, 2012. - ISBN 3-936338-28-0, p. 888-895
10.4229/27thEUPVSEC2012-2DO.8.4
Abstract:
The interface passivation of a-AlOx/a-SiNx:H stacks deposited on p-type silicon by in-line plasma enhanced chemical vapor deposition is investigated by means of charge carrier lifetime, field dependent surface photovoltage and capacitance voltage measurements as well as Fourier transform infrared spectroscopy. To control the quality of the interface, we performed different wet chemical surface preparation steps prior to a-AlOx/a-SiNx:H stack deposition. Our investigation is focusing on the interface passivation upon post-deposition thermal treatments such as annealing at 425 °C and firing at 860 °C as applied in the silicon solar cell industry. We demonstrate that the interface recombination is mainly controlled by the interface state density as demonstrated by the correlation between the surface recombination velocity and interface state density inferred from lifetime and SPV measurements. The increase of the negative charge density after thermal steps as revealed by capacitance-voltage measurements correlates with the increase of the density of negatively charged AlO4 tetrahedra as revealed by infrared spectroscopy suggesting that the tetrahedrally coordinated Al contribute to the formation of the negative charge.