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Improved Emitters by Dry Etching
J. Seiffe, R. Khandelwal, C. Clement, U. Jäger, M. Hofmann, J. Rentsch, R. Preu
Passivation, PECVD, Selective Emitter, Dry Etching, Silicon Nitride
Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic: Mono- and Multicrystalline Silicon Materials and Cells
Event: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain
Session: 2CV.2.71
1965 - 1968
ISBN: 3-936338-26-4
Paper DOI: 10.4229/25thEUPVSEC2010-2CV.2.71
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A selective emitter by means of lowly doped regions with a low saturation current between the contact fingers and highly doped regions below the fingers can significantly improve the cell efficiency of crystalline silicon solar cells. A low saturation current could be achieved for diffused emitters by etching back the surface layer containing the high concentration of electrical inactive phosphorous (“dead-layer”). The significant benefit of performing this etch-process with plasma is the possibility to include it in one vacuum chamber with a subsequent anti-reflection coating (ARC). In this work a homogeneous etch-back of the emitter by means of SF6-plasma-etching is presented. The passivation quality of a silicon nitride ARC and of a silicon-rich silicon oxynitride / silicon nitride double layer ARC deposited on plasma-etched emitters is investigated. Emitter saturation currents down to J0e = 57 fA/cm2 are achieved.