Solar-Grade Silicon from Metallurgical-Grade Silicon Via Iodine Chemical Vapor Transport Purification

T. F. Ciszek; T. H. Wang; M. R. Page; R. E. Bauer; M. D. Landry

Solar-Grade Silicon from Metallurgical-Grade Silicon Via Iodine Chemical Vapor Transport Purification

T. F. Ciszek, T. H. Wang, M. R. Page, R. E. Bauer, M. D. Landry

Chemistry and Nanoscience

National Renewable Energy Laboratory

Research output: Contribution to conference › Paper › peer-review

6 Scopus Citations

Abstract

In an atmospheric-pressure "open" reactor, SiI₂ transfers from a hot (>1100°C) Si source to a cooler (>750°C) Si substrate and decomposes easily via 2SiI₂ → Si + SiI₄ with up to 5μm/min deposition rate. SiI₄ returns to cyclically transport more Si. When the source is metallurgical-grade Si, impurities can be effectively removed by three mechanisms: (1) differing free energies of formation in forming silicon and impurity iodides; (2) distillation; and (3) differing standard free energies of formation during deposition. Distillation has been previously reported. Here, we focused on mechanisms (1) and (3). We made feedstock, analyzed the impurity levels, grew Czochralski single crystals, and evaluated crystal and photovoltaic properties. Cell efficiencies of 9.5% were obtained. Incorporating distillation (step 2) should increase this to a viable level.

Original language	American English
Pages	206-209
Number of pages	4
State	Published - 2002
Event	29th IEEE Photovoltaic Specialists Conference - New Orleans, LA, United States Duration: 19 May 2002 → 24 May 2002

Conference

Conference	29th IEEE Photovoltaic Specialists Conference
Country/Territory	United States
City	New Orleans, LA
Period	19/05/02 → 24/05/02

Bibliographical note

For preprint version including full text online document, see NREL/CP-520-31443

NREL Publication Number

NREL/CP-520-33687

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Cite this

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title = "Solar-Grade Silicon from Metallurgical-Grade Silicon Via Iodine Chemical Vapor Transport Purification",

abstract = "In an atmospheric-pressure {"}open{"} reactor, SiI2 transfers from a hot (>1100°C) Si source to a cooler (>750°C) Si substrate and decomposes easily via 2SiI2 → Si + SiI4 with up to 5μm/min deposition rate. SiI4 returns to cyclically transport more Si. When the source is metallurgical-grade Si, impurities can be effectively removed by three mechanisms: (1) differing free energies of formation in forming silicon and impurity iodides; (2) distillation; and (3) differing standard free energies of formation during deposition. Distillation has been previously reported. Here, we focused on mechanisms (1) and (3). We made feedstock, analyzed the impurity levels, grew Czochralski single crystals, and evaluated crystal and photovoltaic properties. Cell efficiencies of 9.5% were obtained. Incorporating distillation (step 2) should increase this to a viable level.",

author = "Ciszek, {T. F.} and Wang, {T. H.} and Page, {M. R.} and Bauer, {R. E.} and Landry, {M. D.}",

note = "For preprint version including full text online document, see NREL/CP-520-31443; 29th IEEE Photovoltaic Specialists Conference ; Conference date: 19-05-2002 Through 24-05-2002",

year = "2002",

language = "American English",

pages = "206--209",

}

TY - CONF

T1 - Solar-Grade Silicon from Metallurgical-Grade Silicon Via Iodine Chemical Vapor Transport Purification

AU - Ciszek, T. F.

AU - Wang, T. H.

AU - Page, M. R.

AU - Bauer, R. E.

AU - Landry, M. D.

N1 - For preprint version including full text online document, see NREL/CP-520-31443

PY - 2002

Y1 - 2002

N2 - In an atmospheric-pressure "open" reactor, SiI2 transfers from a hot (>1100°C) Si source to a cooler (>750°C) Si substrate and decomposes easily via 2SiI2 → Si + SiI4 with up to 5μm/min deposition rate. SiI4 returns to cyclically transport more Si. When the source is metallurgical-grade Si, impurities can be effectively removed by three mechanisms: (1) differing free energies of formation in forming silicon and impurity iodides; (2) distillation; and (3) differing standard free energies of formation during deposition. Distillation has been previously reported. Here, we focused on mechanisms (1) and (3). We made feedstock, analyzed the impurity levels, grew Czochralski single crystals, and evaluated crystal and photovoltaic properties. Cell efficiencies of 9.5% were obtained. Incorporating distillation (step 2) should increase this to a viable level.

AB - In an atmospheric-pressure "open" reactor, SiI2 transfers from a hot (>1100°C) Si source to a cooler (>750°C) Si substrate and decomposes easily via 2SiI2 → Si + SiI4 with up to 5μm/min deposition rate. SiI4 returns to cyclically transport more Si. When the source is metallurgical-grade Si, impurities can be effectively removed by three mechanisms: (1) differing free energies of formation in forming silicon and impurity iodides; (2) distillation; and (3) differing standard free energies of formation during deposition. Distillation has been previously reported. Here, we focused on mechanisms (1) and (3). We made feedstock, analyzed the impurity levels, grew Czochralski single crystals, and evaluated crystal and photovoltaic properties. Cell efficiencies of 9.5% were obtained. Incorporating distillation (step 2) should increase this to a viable level.

UR - http://www.scopus.com/inward/record.url?scp=0036953389&partnerID=8YFLogxK

M3 - Paper

AN - SCOPUS:0036953389

SP - 206

EP - 209

T2 - 29th IEEE Photovoltaic Specialists Conference

Y2 - 19 May 2002 through 24 May 2002

ER -

Solar-Grade Silicon from Metallurgical-Grade Silicon Via Iodine Chemical Vapor Transport Purification

Abstract

Conference

Bibliographical note

NREL Publication Number

UN SDGs

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Cite this