Surface chemistry during porous-silicon formation in dilute fluoride electrolytes

A. Belaïdi, M. Safi, F. Ozanam, J. N. Chazalviel, O. Gorochov

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Abstract

In contrast to previous belief, we show that oxide is present at the silicon/dilute-fluoride electrolyte interface even near the onset of anodic current, which corresponds to the regime of porous-silicon formation. This point is supported by the observation of a transient anodic current when the potential is maintained in this region until a steady-state current is reached, then stepped to a value near that of the open-circuit potential. In situ infrared investigations confirm the presence of a submonolayer oxide film. Upon polarizing the interface, the electrochemical current and the surface concentrations of oxide and hydrogen exhibit slow relaxations. These transient features are accounted for in a simple kinetic model, which assumes two parallel dissolution pathways and a slow, potential-dependent relaxation of the electrochemically active surface area. In this framework, the transition to the electropolishing regime is found to correspond to unit coverage of the electrochemically active surface by the oxide.

Original languageEnglish
Pages (from-to)2659-2664
Number of pages6
JournalJournal of the Electrochemical Society
Volume146
Issue number7
DOIs
Publication statusPublished - 1 Jul 1999

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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