Evaluating the Aluminum-Alloyed [Formula Omitted]-Layer of Silicon Solar Cells by Emitter Saturation Current Density and Optical Microspectroscopy Measurements

• Published in: IEEE transactions on electron devices Vol. 58; no. 2; p. 441
• Main Authors: Woehl, Robert, Gundel, Paul, Krause, Jonas, Ruhle, Karola, Heinz, Friedemann D, Rauer, Michael, Schmiga, Christian, Schubert, Martin C, Warta, Wilhelm, Biro, Daniel
• Format: Journal Article
• Language: English
• Published: New York The Institute of Electrical and Electronics Engineers, Inc. (IEEE) 01.02.2011
• Subjects: Aluminum
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2010.2093145

Surface-passivated and surface-unpassivated aluminum-alloyed -layers are characterized. By varying the firing conditions and the thickness of the screen-printed aluminum paste, different sheet resistances of the -layer were fabricated. The emitter saturation current density plotted versus follows distinctly different trends for the passivated and unpassivated samples. An aluminum paste with a boron additive achieves a much higher doping concentration and a lower sheet resistance but nevertheless follows the same curves as the pure Al paste. The aluminum -layer was quantitatively analyzed with microphotoluminescence and Fano-Raman measurements. The latter shows an increased defect recombination at the interface between the -layer and the moderately doped Si bulk. The lower Shockley-Read-Hall lifetime in this region can be attributed to a high defect concentration in the most highly doped layer, represents an impediment to the reduction of for Al-doped emitter regions, and needs to be optimized in future investigations.