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

Research output: Contribution to journalArticlepeer-review

10 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 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.

Original languageAmerican English
Pages (from-to)6629-6636
Number of pages8
JournalACS Applied Nano Materials
Volume4
Issue number7
DOIs
StatePublished - 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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