High temperature oxidation pre-treatment of textured c-Si wafers passivated by a-Si:H

G. Limodio*, G. D'Herouville, L. Mazzarella, Y. Zhao, G. Yang, O. Isabella, M. Zeman

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
29 Downloads (Pure)

Abstract

This work shows an alternative surface cleaning method for c-Si wafers to replace the standard chemical procedures as RCA or HNO 3 which involve hazardous chemicals or unstable processes. The method consists in a high-temperature oxidation treatment (HTO) performed in a classical tube furnace that incorporates organic and metal particles present on the c-Si surfaces in the growing SiO 2 layer. The result is as a reliable pre-treatment method for obtaining less defective c-Si surfaces ready for solar cell fabrication after SiO 2 removal. To test the surface passivation quality obtained with our alternative cleaning method, we grow amorphous silicon (a-Si:H) layers by plasma enhanced chemical vapor deposition on both sides of the c-Si wafer and systematically compare the effective carrier lifetime (τ eff ) and implied V OC (iV oc ) to the wafer treated with the standard cleaning in our laboratory. We optimize HTO treatment time reaching τ eff of ∼6 ms and iV oc of 721 mV for the best sample. We ascribe the improved passivation quality using HTO to two concurrent factors. Firstly, the encapsulation of defects into SiO 2 layer that is then etched prior a-Si:H deposition and secondly, to modification of the pyramids’ morphology that facilitates the surface passivation. SEM pictures and reflection measurements support the latter hypothesis.

Original languageEnglish
Pages (from-to)67-70
Number of pages4
JournalMaterials Science in Semiconductor Processing
Volume97
DOIs
Publication statusPublished - 2019

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Keywords

  • Amorphous silicon passivation
  • Defect encapsulation
  • Silicon heterojunction solar cells
  • Thermal oxidation

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