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8 September 2011 Lowest surface recombination velocity on n-type crystalline silicon using PECVD a-Si:H/SiNx bi-layer passivation
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Proceedings Volume 8007, Photonics North 2011; 800720 (2011)
Event: Photonics North 2011, 2011, Ottawa, Canada
Energy conversion efficiency of crystalline silicon (c-Si) solar cells manufactured on thin substrates is strongly influenced by the recombination losses of photo-generated charge carriers at the surface and in its proximity. Intrinsic hydrogenated amorphous silicon (i-a-Si:H) deposited using DC saddle-field plasma enhanced chemical vapour deposition (PECVD) at a low temperature of ~200°C reduces recombination losses of photo-generated carriers through passivation of defects at the surface. This study reports on high quality surface passivation achieved using a dual layer approach wherein a 70nm amorphous silicon nitride (SiNx) capping layer is deposited on a less than 10nm thin i-a-Si:H layer. While the a-Si:H layer is effective in passivating the interface recombination sites, SiNx is deemed to incorporate field-effect passivation, thus providing a minority carrier mirror. Additionally, SiNx layer acts as an anti-reflection coating with a low absorption coefficient in the optical frequency range of interest. The SiNx deposition conditions, known to strongly influence the passivating quality of the dual layer structure, were systematically investigated using the response surface methodology (RSM). The optimal deposition parameters obtained from the RSM study were experimentally verified to yield the lowest surface recombination velocity of 3.5 cm/s on 1-2 Ω-cm n-type FZ c-Si using a PECVD a-Si:H/SiNx bi-layer passivation stack.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dmitri S. Stepanov, Zahidur R. Chowdhury, and Nazir P. Kherani "Lowest surface recombination velocity on n-type crystalline silicon using PECVD a-Si:H/SiNx bi-layer passivation", Proc. SPIE 8007, Photonics North 2011, 800720 (8 September 2011);

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