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2005
Conference Paper
Titel
Progress in the use of sprayed phosphoric acid as an inexpensive dopant source for industrial solar cells
Abstract
An in-line emitter formation process in which dilute phosphoric acid is sprayed by means of an ultrasonic nozzle on the wafers prior to the high-temperature treatment was developed, investigated and used to fabricate solar cells. The spray solution consisted of 3% w/w phosphoric acid and of a small quantity of two surfactants. The surfactants make it possible that the sprayed liquid, as well as the phosphosilicate glass (PSG) formed in the furnace, completely cover the silicon surface. The PSG became thicker with increasing flow rate of the spray head, whereas sheet resistance (Rsh) first decreased and then increased with increasing PSG thickness. Solar cells were fabricated on 125Ã 125 mm2 mc-Si untextured wafers. Sheet resistance was in the range of 42 to 50 Î/sq with a standard deviation across a wafer of approx. 2.2 Î/sq. The cells yielded efficiencies up to 14.9%.
Author(s)