Electrochemical impedance spectroscopy of oxidized porous silicon

Guido Mula*, Maria V. Tiddia, Roberta Ruffilli, Andrea Falqui, Simonetta Palmas, Michele Mascia

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25-22 μm) and of the applied current density (1.1-11.1 mA/cm2, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process.

Original languageEnglish (US)
Pages (from-to)311-316
Number of pages6
JournalThin Solid Films
Volume556
DOIs
StatePublished - Apr 1 2014

Keywords

  • Electrochemical oxidation
  • Energy dispersive spectroscopy
  • Galvanostatic electrochemical impedance spectroscopy
  • Optical reflectivity
  • Porous silicon
  • Refractive index
  • Scanning electron microscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Metals and Alloys
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

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