Atomic-layer deposited Nb2O5 as transparent passivating electron contact for c-Si solar cells

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Abstract

Passivating contacts based on metal oxides have proven to enable high energy conversion efficiencies for crystalline silicon (c-Si) solar cells at low processing complexity. In this work, the potential of atomic-layer deposited (ALD) Nb2O5 as novel electron-selective passivating contact is explored in terms of recombination parameter J0 and contact resistivity ρc. It is shown that after forming gas annealing, ALD Nb2O5 can provide adequate surface passivation with J0 values down to 25–30 fA/cm2. On HF-treated c-Si surfaces a minimum film thickness of ~ 3 nm is required to achieve this high level of passivation, whereas on surfaces with a wet-chemical SiO2 interlayer the high passivation level is persistent down to film thicknesses of only 1 nm. Ohmic n-type contacts have been achieved using Al as contacting metal, where annealing the samples after Al contacting proved crucial for obtaining good contact properties. Low contact resistivity values of 70 and 124 mΩ cm2 for 1 and 2 nm Nb2O5 films, respectively, have been achieved on c-Si substrates that received an HF treatment prior to Nb2O5 deposition. Transmission electron microscopy imaging shows that on such surfaces the annealing treatment leads to the formation of a (1.7 ± 0.2) nm interfacial oxide in between the c-Si substrate and the Nb2O5 film. The presented results demonstrate the potential of ALD Nb2O5 as electron-selective passivating contact and directions for future research are outlined.

Original languageEnglish
Pages (from-to)98-104
Number of pages7
JournalSolar Energy Materials and Solar Cells
Volume184
Early online date15 May 2018
DOIs
Publication statusPublished - 1 Sep 2018

Fingerprint

Silicon solar cells
Silicon
Passivation
Crystalline materials
Electrons
Annealing
Oxides
Film thickness
Metals
Substrates
Energy conversion
Conversion efficiency
Gases
Transmission electron microscopy
Imaging techniques
Processing

Keywords

  • Atomic layer deposition
  • Crystalline silicon solar cells
  • Passivating contact
  • Passivation

Cite this

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title = "Atomic-layer deposited Nb2O5 as transparent passivating electron contact for c-Si solar cells",
abstract = "Passivating contacts based on metal oxides have proven to enable high energy conversion efficiencies for crystalline silicon (c-Si) solar cells at low processing complexity. In this work, the potential of atomic-layer deposited (ALD) Nb2O5 as novel electron-selective passivating contact is explored in terms of recombination parameter J0 and contact resistivity ρc. It is shown that after forming gas annealing, ALD Nb2O5 can provide adequate surface passivation with J0 values down to 25–30 fA/cm2. On HF-treated c-Si surfaces a minimum film thickness of ~ 3 nm is required to achieve this high level of passivation, whereas on surfaces with a wet-chemical SiO2 interlayer the high passivation level is persistent down to film thicknesses of only 1 nm. Ohmic n-type contacts have been achieved using Al as contacting metal, where annealing the samples after Al contacting proved crucial for obtaining good contact properties. Low contact resistivity values of 70 and 124 mΩ cm2 for 1 and 2 nm Nb2O5 films, respectively, have been achieved on c-Si substrates that received an HF treatment prior to Nb2O5 deposition. Transmission electron microscopy imaging shows that on such surfaces the annealing treatment leads to the formation of a (1.7 ± 0.2) nm interfacial oxide in between the c-Si substrate and the Nb2O5 film. The presented results demonstrate the potential of ALD Nb2O5 as electron-selective passivating contact and directions for future research are outlined.",
keywords = "Atomic layer deposition, Crystalline silicon solar cells, Passivating contact, Passivation",
author = "Bart Macco and Black, {Lachlan E.} and Jimmy Melskens and {van de Loo}, {Bas W.H.} and Berghuis, {Willem Jan H.} and Verheijen, {Marcel A.} and Kessels, {Wilhelmus M.M.}",
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language = "English",
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pages = "98--104",
journal = "Solar Energy Materials and Solar Cells",
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Atomic-layer deposited Nb2O5 as transparent passivating electron contact for c-Si solar cells. / Macco, Bart; Black, Lachlan E.; Melskens, Jimmy; van de Loo, Bas W.H.; Berghuis, Willem Jan H.; Verheijen, Marcel A.; Kessels, Wilhelmus M.M.

In: Solar Energy Materials and Solar Cells, Vol. 184, 01.09.2018, p. 98-104.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Atomic-layer deposited Nb2O5 as transparent passivating electron contact for c-Si solar cells

AU - Macco, Bart

AU - Black, Lachlan E.

AU - Melskens, Jimmy

AU - van de Loo, Bas W.H.

AU - Berghuis, Willem Jan H.

AU - Verheijen, Marcel A.

AU - Kessels, Wilhelmus M.M.

PY - 2018/9/1

Y1 - 2018/9/1

N2 - Passivating contacts based on metal oxides have proven to enable high energy conversion efficiencies for crystalline silicon (c-Si) solar cells at low processing complexity. In this work, the potential of atomic-layer deposited (ALD) Nb2O5 as novel electron-selective passivating contact is explored in terms of recombination parameter J0 and contact resistivity ρc. It is shown that after forming gas annealing, ALD Nb2O5 can provide adequate surface passivation with J0 values down to 25–30 fA/cm2. On HF-treated c-Si surfaces a minimum film thickness of ~ 3 nm is required to achieve this high level of passivation, whereas on surfaces with a wet-chemical SiO2 interlayer the high passivation level is persistent down to film thicknesses of only 1 nm. Ohmic n-type contacts have been achieved using Al as contacting metal, where annealing the samples after Al contacting proved crucial for obtaining good contact properties. Low contact resistivity values of 70 and 124 mΩ cm2 for 1 and 2 nm Nb2O5 films, respectively, have been achieved on c-Si substrates that received an HF treatment prior to Nb2O5 deposition. Transmission electron microscopy imaging shows that on such surfaces the annealing treatment leads to the formation of a (1.7 ± 0.2) nm interfacial oxide in between the c-Si substrate and the Nb2O5 film. The presented results demonstrate the potential of ALD Nb2O5 as electron-selective passivating contact and directions for future research are outlined.

AB - Passivating contacts based on metal oxides have proven to enable high energy conversion efficiencies for crystalline silicon (c-Si) solar cells at low processing complexity. In this work, the potential of atomic-layer deposited (ALD) Nb2O5 as novel electron-selective passivating contact is explored in terms of recombination parameter J0 and contact resistivity ρc. It is shown that after forming gas annealing, ALD Nb2O5 can provide adequate surface passivation with J0 values down to 25–30 fA/cm2. On HF-treated c-Si surfaces a minimum film thickness of ~ 3 nm is required to achieve this high level of passivation, whereas on surfaces with a wet-chemical SiO2 interlayer the high passivation level is persistent down to film thicknesses of only 1 nm. Ohmic n-type contacts have been achieved using Al as contacting metal, where annealing the samples after Al contacting proved crucial for obtaining good contact properties. Low contact resistivity values of 70 and 124 mΩ cm2 for 1 and 2 nm Nb2O5 films, respectively, have been achieved on c-Si substrates that received an HF treatment prior to Nb2O5 deposition. Transmission electron microscopy imaging shows that on such surfaces the annealing treatment leads to the formation of a (1.7 ± 0.2) nm interfacial oxide in between the c-Si substrate and the Nb2O5 film. The presented results demonstrate the potential of ALD Nb2O5 as electron-selective passivating contact and directions for future research are outlined.

KW - Atomic layer deposition

KW - Crystalline silicon solar cells

KW - Passivating contact

KW - Passivation

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U2 - 10.1016/j.solmat.2018.04.037

DO - 10.1016/j.solmat.2018.04.037

M3 - Article

AN - SCOPUS:85046762343

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JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

SN - 0927-0248

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