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X-Ray Photoelectron Spectroscopy (XPS) Study of the Printed-SiOx DL CAP in PERC-Type Solar Cell Application
Y.-S. Lin, J.-Y. Hung, C.-H. Ku, J.-C. Wang, J. Yu, S.-L. Lee, T.-C. Chen, T.-W. Kuo, C.-C. Wen, Y.-C. Lee, I.-S. Yu
PERC, Paste, AlOx, SiOx
Silicon Cells
Subtopic: Homojunction Solar Cells
Event: 35th European Photovoltaic Solar Energy Conference and Exhibition
Session: 2AV.2.24
577 - 579
ISBN: 3-936338-50-7
Paper DOI: 10.4229/35thEUPVSEC20182018-2AV.2.24
0,00 EUR
Document(s): paper, poster


In our previous work, we demonstrated that an efficiency gain of 0.13 % can be achieved by implementing a dual capping (DL CAP, SiOx/SiNx) layer on our unique printed-AlOx passivated emitter and rear cells (PERC) technology. The SiOx layer was deposited by using screen printing and was confirmed to be a composite of SiO2 and Si(OH)x by using Fourier-transform infrared spectroscopy (FT-IR) analysis. The Si(OH)x was speculated to be an oxidizing-agent provider which decomposes during firing, and then the released oxidizing agents diffuse to and oxidize the AlOx/Si interface as a result of the reduction in the interface trap density (Dit) and better passivation quality In this work, we further analyzed the elemental composition and the electronic state of the elements of DL CAP and baseline (BSL) by using X-ray photoelectron spectroscopy (XPS) depth profile analysis. XPS result confirmed that DL CAP has a higher degree of oxidation than BSL do at the AlOx/Si interface (O atomic %: 24.3 in DL CAP vs. 18.1 in BSL). Moreover, the binding energy of O 1s is about 534.1 eV in the printed SiOx layer and shifts towards lower bonding energy of 532.7 eV as approaching the AlOx/Si interface, meaning transformation from hydroxide to oxide as approaching the AlOx/Si interface. These XPS results are consistent with the FT-IR results and are as the supporting evidence for the passivation mechanism we speculated..