Hydrogen-Assisted Defect Engineering of Doped Poly-Si Films for Passivating Contact Solar Cells

Steven Harvey, Matthew Young, Mowafak Al-Jassim, Thien Truong, Di Yan, Christian Samundsett, Anyao Liu, Zetao Ding, Mike Tebyetekerwa, Felipe Kremer, Andres Cuevas, Daniel Macdonald, Hieu Nguyen

Research output: Contribution to journalArticlepeer-review

11 Scopus Citations

Abstract

Hydrogen-assisted defect engineering, via a hydrogenated silicon nitride (SiNx:H) capping layer, on doped polycrystalline silicon (poly-Si) passivating-contact structures, is explored using complementary techniques. The hydrogen treatment universally improves the passivation quality of poly-Si/SiOx stacks on all samples investigated. Meanwhile, their contact resistivity remains very low at ∼6 mω·cm2. Moreover, the nature of charge carrier recombination within the poly-Si films is also investigated by means of photoluminescence. On planar c-Si substrates, the poly-Si films emit two broad photoluminescence peaks at ∼850-1050 and ∼1300-1500 nm. The former is the characteristic peak of the hydrogenated amorphous Si (a-Si:H) phase and only appears after the treatment, demonstrating that (i) a significant amount of hydrogen has been driven into the poly-Si film and (ii) an amorphous phase is present within it. The second peak originates from sub-band-gap radiative defects inside the poly-Si films and increases after the treatment, suggesting a suppression of their nonradiative recombination channels. For films deposited on textured c-Si substrates, there is a disrupted oxide boundary, preventing a buildup of excess carriers inside the films and leading to quenching of the film luminescence.

Original languageAmerican English
Pages (from-to)8783-8791
Number of pages9
JournalACS Applied Energy Materials
Volume2
Issue number12
DOIs
StatePublished - 23 Dec 2019

Bibliographical note

Publisher Copyright:
© 2019 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-74683

Keywords

  • amorphous silicon
  • doped polycrystalline silicon
  • hydrogenation
  • passivating contacts
  • photoluminescence

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