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Influence of precursor layer ablation on laser doping of silicon
Author(s) -
Köhler J. R.,
Eisele S.
Publication year - 2010
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.968
Subject(s) - dopant , materials science , laser ablation , doping , silicon , laser , layer (electronics) , ablation , analytical chemistry (journal) , pulsed laser deposition , optics , optoelectronics , thin film , nanotechnology , chemistry , physics , engineering , chromatography , aerospace engineering
This paper presents a numerical model, which quantitatively demonstrates that ablation and partial recondensation of the dopant precursor layer are some of the dominating physical processes in laser doping (LD) of crystalline silicon. Our pulsed LD process uses a line focused laser beam, enabling the creation of solar cell emitters without the generation of dislocations, if the width w of the short axis of the line focus is w < 10 μm. The concentration profiles of the dopant atoms strongly depend on the pulse energy density E p , the pulse to pulse separation Δ x and the number of laser scans N s . By comparing measured with modeled concentration profiles, we are able to evaluate the ablation width as well as the amount of the ablated precursor layer. In case of a sputtered phosphorus precursor layer, the ablation width w a is w a = 6 μm, whereas the width of the molten silicon layer w m is w m = 5 μm. The model also explains the dependence of experimental dopant concentration profiles on the number of subsequent laser scans N s and pulse to pulse separation Δ x . Copyright © 2010 John Wiley & Sons, Ltd.