Chemical Passivation of Crystalline Si by Al2O3 Deposited Using Atomic Layer Deposition: Implications for Solar Cells

Abigail Meyer; Rohan Chaulkukar; Noemi Leick; William Nemeth; David Young; Paul Stradins; Sumit Agarwal

doi:10.1021/acsanm.1c00448

Chemical Passivation of Crystalline Si by Al2O3 Deposited Using Atomic Layer Deposition: Implications for Solar Cells

Abigail Meyer, Rohan Chaulkukar, Noemi Leick, William Nemeth, David Young, Paul Stradins, Sumit Agarwal

Chemistry and Nanoscience

Colorado School of Mines

Research output: Contribution to journal › Article › peer-review

11 Scopus Citations

Abstract

The atomistic-level mechanism for the chemical passivation of the monocrystalline Si (c-Si) surface with thermally annealed Al₂O₃was studied using in situ infrared spectroscopy and photoconductance decay measurements. Al₂O₃was deposited on high-lifetime, float-zonec-Si substrates using atomic layer deposition (ALD) from trimethylaluminum (TMA), and H₂O or O₃. Surface-sensitive attenuated total reflection Fourier transform infrared spectroscopy was used to monitor thec-Si/Al₂O₃interface, as well as the bulk of the Al₂O₃film during the entire process. Our results show that some surface Si-H bonds are preserved after the ALD of Al₂O₃on H-terminated Si. During the annealing step at 400 °C, restructuring occurs at thec-Si/Al₂O₃interface to form interfacial SiO_x. Isotope labeling was used to differentiate interfacial SiD bonds on thec-Si surface from H incorporated in Al₂O₃. Within the sensitivity of our infrared setup (∼10¹³cm^-2), we did not observe any net migration of atomic H or D from Al₂O₃to thec-Si/Al₂O₃interface. To isolate the effects of chemical and field-effect passivation of Al₂O₃thin films, we carried out surface passivation studies onc-Si/SiO₂/Al₂O₃stacks. We also annealed these stacks in different atmospheres to test the influence of annealing atmospheres on the chemical passivation ofc-Si by Al₂O₃and observed that O₂-containing atmosphere led to the best surface chemical passivation.

Original language	American English
Pages (from-to)	6629-6636
Number of pages	8
Journal	ACS Applied Nano Materials
Volume	4
Issue number	7
DOIs	https://doi.org/10.1021/acsanm.1c00448 https://doi.org/10.1021/acsanm.1c00448
State	Published - 23 Jul 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society

NREL Publication Number

NREL/JA-5900-80036

Keywords

Al2O3
ATF-FTIR spectroscopy
atomic layer deposition
silicon solar cells
surface passivation

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title = "Chemical Passivation of Crystalline Si by Al2O3 Deposited Using Atomic Layer Deposition: Implications for Solar Cells",

abstract = "The atomistic-level mechanism for the chemical passivation of the monocrystalline Si (c-Si) surface with thermally annealed Al2O3was studied using in situ infrared spectroscopy and photoconductance decay measurements. Al2O3was deposited on high-lifetime, float-zonec-Si substrates using atomic layer deposition (ALD) from trimethylaluminum (TMA), and H2O or O3. Surface-sensitive attenuated total reflection Fourier transform infrared spectroscopy was used to monitor thec-Si/Al2O3interface, as well as the bulk of the Al2O3film during the entire process. Our results show that some surface Si-H bonds are preserved after the ALD of Al2O3on H-terminated Si. During the annealing step at 400 °C, restructuring occurs at thec-Si/Al2O3interface to form interfacial SiOx. Isotope labeling was used to differentiate interfacial SiD bonds on thec-Si surface from H incorporated in Al2O3. Within the sensitivity of our infrared setup (∼1013cm-2), we did not observe any net migration of atomic H or D from Al2O3to thec-Si/Al2O3interface. To isolate the effects of chemical and field-effect passivation of Al2O3thin films, we carried out surface passivation studies onc-Si/SiO2/Al2O3stacks. We also annealed these stacks in different atmospheres to test the influence of annealing atmospheres on the chemical passivation ofc-Si by Al2O3and observed that O2-containing atmosphere led to the best surface chemical passivation.",

keywords = "Al2O3, ATF-FTIR spectroscopy, atomic layer deposition, silicon solar cells, surface passivation",

author = "Abigail Meyer and Rohan Chaulkukar and Noemi Leick and William Nemeth and David Young and Paul Stradins and Sumit Agarwal",

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year = "2021",

month = jul,

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doi = "10.1021/acsanm.1c00448",

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T1 - Chemical Passivation of Crystalline Si by Al2O3 Deposited Using Atomic Layer Deposition: Implications for Solar Cells

AU - Meyer, Abigail

AU - Chaulkukar, Rohan

AU - Leick, Noemi

AU - Nemeth, William

AU - Young, David

AU - Stradins, Paul

AU - Agarwal, Sumit

PY - 2021/7/23

Y1 - 2021/7/23

N2 - The atomistic-level mechanism for the chemical passivation of the monocrystalline Si (c-Si) surface with thermally annealed Al2O3was studied using in situ infrared spectroscopy and photoconductance decay measurements. Al2O3was deposited on high-lifetime, float-zonec-Si substrates using atomic layer deposition (ALD) from trimethylaluminum (TMA), and H2O or O3. Surface-sensitive attenuated total reflection Fourier transform infrared spectroscopy was used to monitor thec-Si/Al2O3interface, as well as the bulk of the Al2O3film during the entire process. Our results show that some surface Si-H bonds are preserved after the ALD of Al2O3on H-terminated Si. During the annealing step at 400 °C, restructuring occurs at thec-Si/Al2O3interface to form interfacial SiOx. Isotope labeling was used to differentiate interfacial SiD bonds on thec-Si surface from H incorporated in Al2O3. Within the sensitivity of our infrared setup (∼1013cm-2), we did not observe any net migration of atomic H or D from Al2O3to thec-Si/Al2O3interface. To isolate the effects of chemical and field-effect passivation of Al2O3thin films, we carried out surface passivation studies onc-Si/SiO2/Al2O3stacks. We also annealed these stacks in different atmospheres to test the influence of annealing atmospheres on the chemical passivation ofc-Si by Al2O3and observed that O2-containing atmosphere led to the best surface chemical passivation.

AB - The atomistic-level mechanism for the chemical passivation of the monocrystalline Si (c-Si) surface with thermally annealed Al2O3was studied using in situ infrared spectroscopy and photoconductance decay measurements. Al2O3was deposited on high-lifetime, float-zonec-Si substrates using atomic layer deposition (ALD) from trimethylaluminum (TMA), and H2O or O3. Surface-sensitive attenuated total reflection Fourier transform infrared spectroscopy was used to monitor thec-Si/Al2O3interface, as well as the bulk of the Al2O3film during the entire process. Our results show that some surface Si-H bonds are preserved after the ALD of Al2O3on H-terminated Si. During the annealing step at 400 °C, restructuring occurs at thec-Si/Al2O3interface to form interfacial SiOx. Isotope labeling was used to differentiate interfacial SiD bonds on thec-Si surface from H incorporated in Al2O3. Within the sensitivity of our infrared setup (∼1013cm-2), we did not observe any net migration of atomic H or D from Al2O3to thec-Si/Al2O3interface. To isolate the effects of chemical and field-effect passivation of Al2O3thin films, we carried out surface passivation studies onc-Si/SiO2/Al2O3stacks. We also annealed these stacks in different atmospheres to test the influence of annealing atmospheres on the chemical passivation ofc-Si by Al2O3and observed that O2-containing atmosphere led to the best surface chemical passivation.

KW - Al2O3

KW - ATF-FTIR spectroscopy

KW - atomic layer deposition

KW - silicon solar cells

KW - surface passivation

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DO - 10.1021/acsanm.1c00448

M3 - Article

AN - SCOPUS:85110366892

SN - 2574-0970

VL - 4

SP - 6629

EP - 6636

JO - ACS Applied Nano Materials

JF - ACS Applied Nano Materials

IS - 7

ER -

Chemical Passivation of Crystalline Si by Al2O3 Deposited Using Atomic Layer Deposition: Implications for Solar Cells

Abstract

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