NDLI: Low resistance screen-printed Ag contacts to POCl emitters with low saturation current density for high efficiency Si solar cells

Content Provider	IEEE Xplore Digital Library
Author	Cooper, I.B. Tate, K. Carroll, A.F. Mikeska, K.R. Reedy, R.C. Rohatgi, A.
Copyright Year	2012
Description	Author affiliation: DuPont Microcircuit Materials, Research Triangle Park, NC, USA (Carroll, A.F.) \|\| National Renewable Energy Laboratory, Golden, CO, USA (Reedy, R.C.) \|\| DuPont Central Research and Development, Wilmington, DE, USA (Mikeska, K.R.) \|\| University Center of Excellence for Photovoltaics Research and Education, Georgia Institute of Technology, Atlanta, USA (Cooper, I.B.; Tate, K.; Rohatgi, A.)
Abstract	The silicon (Si) PV industry recognizes the value of phosphorus (P) emitters with low saturation current density (J) for ability to produce high final cell open circuit voltage (V). However, emitters of such quality, which usually display low surface phosphorus concentration ([P]) are notoriously difficult to contact using traditional screen-printed silver (Ag) thick film pastes. Here, we tailored P emitter profiles via POCl diffusion to create solar cell emitters displaying low J values of 67 – 148 $fA/cm^{2}$ and variable electrically active $[P^{surface}]$ of 0.5E20 – 2.0E20 $atoms/cm^{3}$ in order to study the conditions necessary for low resistance contact to such emitters without appreciably deviating from industrial process conditions. Using a screen-printable Ag conductor paste tailored to contact low [P] emitters, we show fill factor (FF) as high as 80% while maintaining V as high as 637 mV on tailored emitters with low J. This results in average solar cell efficiencies of 18.6% with a best efficiency of 18.8%. Series resistance (R) analysis revealed that contact resistance was the major resistive component dictating final R and FF. Finally, microstructural SEM analysis of the Ag/Si contact interface suggested that thin interfacial glass films and extensive Ag precipitate/crystallite surface coverage may explain how such high FF can be attained on emitters with low J and low [P].
Starting Page	003359
Ending Page	003364
File Size	1178631
Page Count	6
File Format	PDF
ISBN	9781467300643
ISSN	01608371
e-ISBN	9781467300667
DOI	10.1109/PVSC.2012.6318292
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2012-06-03
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Photovoltaic cells Resistance Silicon Glass Contact resistance Optical surface waves Films silver contacts metallization photovoltaic cells p-n junctions silicon
Content Type	Text
Resource Type	Article
Subject	Industrial and Manufacturing Engineering Control and Systems Engineering Electrical and Electronic Engineering

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