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Title: Impurity Precipitation, Dissolution, Gettering and Passivation in PV Silicon: Final Technical Report, 30 January 1998--29 August 2001

Abstract

This report describes the major progress in understanding the physics of transition metals in silicon and their possible impact on the efficiency of solar cells that was achieved during the three-year span of this subcontract. We found that metal-silicide precipitates and dissolved 3d transition metals can be relatively easily gettered. Gettering and passivating treatments must take into account the individuality of each transition metal. Our studies demonstrated how significant is the difference between defect reactions of copper and iron. Copper does not significantly affect the minority-carrier diffusion length in p-type silicon, at least as long as its concentration is low, but readily precipitates in n-type silicon. Therefore, copper precipitates may form in the area of p-n junctions and cause shunts in solar cells. Fortunately, copper precipitates are present mostly in the chemical state of copper-silicide and can relatively easily be dissolved. In contrast, iron was found to form clusters of iron-oxides and iron-silicates in the wafers. These clusters are thermodynamically stable even in high temperatures and are extremely difficult to remove. The formation of iron-silicates was observed at temperatures over 900C.

Authors:
Publication Date:
Research Org.:
National Renewable Energy Lab., Golden, CO. (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
15000243
Report Number(s):
NREL/SR-520-31528
XAF-8-17607-04; TRN: US200325%%184
DOE Contract Number:  
AC36-99-GO10337
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Feb 2002; Related Information: Work performed by University of California at Berkeley, Berkeley, California
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; CHEMICAL STATE; DIFFUSION LENGTH; DISSOLUTION; GETTERING; IRON OXIDES; IRON SILICATES; PASSIVATION; P-N JUNCTIONS; PRECIPITATION; SILICON; SOLAR CELLS; TRANSITION ELEMENTS; PV; METAL SILICIDE PRECIPITATES; MINORITY CARRIER DIFFUSION; P-TYPE; X-RAY FLUORESCENCE MICROPROBE ANALYSES; 3D TRANSITION; TRANSIENT ION DRIFT; RECOMBINATION ACTIVITY; BEAM INDUCED CURRENT; MULTICRYSTALLINE SILICON; SOLAR ENERGY - PHOTOVOLTAICS

Citation Formats

Weber, E R. Impurity Precipitation, Dissolution, Gettering and Passivation in PV Silicon: Final Technical Report, 30 January 1998--29 August 2001. United States: N. p., 2002. Web. doi:10.2172/15000243.
Weber, E R. Impurity Precipitation, Dissolution, Gettering and Passivation in PV Silicon: Final Technical Report, 30 January 1998--29 August 2001. United States. doi:10.2172/15000243.
Weber, E R. Fri . "Impurity Precipitation, Dissolution, Gettering and Passivation in PV Silicon: Final Technical Report, 30 January 1998--29 August 2001". United States. doi:10.2172/15000243. https://www.osti.gov/servlets/purl/15000243.
@article{osti_15000243,
title = {Impurity Precipitation, Dissolution, Gettering and Passivation in PV Silicon: Final Technical Report, 30 January 1998--29 August 2001},
author = {Weber, E R},
abstractNote = {This report describes the major progress in understanding the physics of transition metals in silicon and their possible impact on the efficiency of solar cells that was achieved during the three-year span of this subcontract. We found that metal-silicide precipitates and dissolved 3d transition metals can be relatively easily gettered. Gettering and passivating treatments must take into account the individuality of each transition metal. Our studies demonstrated how significant is the difference between defect reactions of copper and iron. Copper does not significantly affect the minority-carrier diffusion length in p-type silicon, at least as long as its concentration is low, but readily precipitates in n-type silicon. Therefore, copper precipitates may form in the area of p-n junctions and cause shunts in solar cells. Fortunately, copper precipitates are present mostly in the chemical state of copper-silicide and can relatively easily be dissolved. In contrast, iron was found to form clusters of iron-oxides and iron-silicates in the wafers. These clusters are thermodynamically stable even in high temperatures and are extremely difficult to remove. The formation of iron-silicates was observed at temperatures over 900C.},
doi = {10.2172/15000243},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2002},
month = {2}
}

Technical Report:

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