Functionalization of hydrofluoric acid‐etched crystalline silicon surfaces were performed using 4‐aminopyridine. This treatment was employed to perform an organic interface with the exterior ambient. The obtained treated surfaces were exposed to different organic vapors while keeping track of their electric conductance to assess their sensing abilities. Results for these tests are provided.

Transmittance measurements at normal incidence were carried out over the visible spectral range for metallic thin films deposited by electron beam evaporation on thick glass substrates. The presence of an inhomogeneous thin layer of Cu2O covering the deposited Cu films is required for a satisfactory model of the measurements taken from various samples with increasing thickness. A spectral projected gradient method is used to invert the transmission spectra from which the wavelength dependence of the effective dielectric function of the oxidized coating layer is obtained. Then an effective medium model is used to estimate the volume fraction of internal voids randomly distributed through the surface layer.

Pulse measurements on the silicon/electrolyte interface have been used to study space-charge layers and surface states on the (100) faces of p-type silicon. The techniques used enable both the creation and study of space-charge layers at the semiconductor surface, ranging from large-depletion to strongaccumulation conditions. They also permit a straightforward separation of the different components of the induced charge at the silicon/electrolyte interface, so as to yield the variation of both the free-electron density in the space-charge layer and the density of occupied surface states with barrier height. The measured space-charge characteristics are in very good agreement with theory. The data in strong-accumulation layers indicate the presence of an insulating buffer layer (such as an oxide), 3-4 monolayers thick. As to surface states, we find that for CP-4-etched silicon, a distribution of states exists ∼ 0.34 eV above the valence-band edge, with total density ∼ 6 × 10 11 cm −2 .

A porous silicon (PSi) chemical sensor for detection of chloride ions in aqueous solution is reported. The sensor setup is based on the semiconductor/electrolyte system used for the analysis of semiconductor surfaces. AC frequency response signals have been obtained in non‐ethanoic and ethanoic solutions containing small concentrations of chloride ions. Discussion of the results is provided. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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