Characterization of different porous silicon structures by spectroscopic ellipsometry

Fried, M.; Lohner, T.; Polgár, O.; Petrik, P.; Vázsonyi, É.; Bársony, I.; Piel, Jean-Philippe; Stehle, Jean-Louis P.

doi:10.1016/0040-6090(95)08058-9

Cited by 54 publications

(26 citation statements)

References 8 publications

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“…Porosity can be modeled with the help of the Bruggeman effective medium approximation [28], because the typical pore dimensions are much less (< 50 nm) than the wavelength of the illuminating light, and so diffraction and non-specular scattering are negligible. The effective medium layers (EML) consisted of varying ratio of monocrystalline silicon (c-Si) and void with additional stoichiometric SiO 2 present in the oxidized samples.…”

Section: Optical Model Developmentmentioning

confidence: 99%

Porosity and thickness characterization of porous Si and oxidized porous Si layers – An ultraviolet–visible–mid infrared ellipsometry study

Fodor

Agócs

Bardet

et al. 2016

Microporous and Mesoporous Materials

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+3620 361 7876This paper suggests the evaluation of morphological parameters of porous silicon layers (PSL) using spectroscopic ellipsometry from UV to midinfrared optical range. PSL were prepared by electrochemical etching of monocrystalline silicon wafers in hydrofluoric acid-based electrolyte. Measuring with an optical and an infrared ellipsometer with a wide spectral range permits an accurate characterization of PSL properties from the top surface to the bottom of the layer with thicknesses from several hundred nanometers up to a few tens of micrometers. Several different optical models for ellipsometric evaluations were developed to determine the thickness, the average porosity, the in-depth porosity gradient, the oxidation level and the surface roughness of the PSL. Porosity was modeled with multiple effective medium layers by varying ratio of crystalline silicon, void and oxidized silicon wherever needed. Thin PSL (< 5 μm) shows no impact of current density on porosity and thickness. However, evaluation of thick PSL (20 -50 μm) highlights the in-depth porosity gradient. Thickness values were also cross-checked with electron microscopy confirming the proposed ellipsometric models. Additionally, different oxidation techniques have also been compared in terms of oxidation level and void content. Volume expansion during PSL oxidation follows exactly the same behavior as that during the oxidation of planar silicon wafers.

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Section: Optical Model Developmentmentioning

confidence: 99%

Porosity and thickness characterization of porous Si and oxidized porous Si layers – An ultraviolet–visible–mid infrared ellipsometry study

Fodor

Agócs

Bardet

et al. 2016

Microporous and Mesoporous Materials

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show abstract

“…Five ellipsometric measurements, containing Porous Silicon [11] (PS, see Fig. 1), were evaluated by using conventional multi-layer optical models.…”

Section: Resultsmentioning

confidence: 99%

Evaluation strategies for multi-layer, multi-material ellipsometric measurements

Polgár

Petrik

Lohner

et al. 2006

Applied Surface Science

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“…It was demonstrated by T. Lohner and co-workers that, depending on the porous silicon structure, the use of fine grain polycrystalline silicon (pc-Si [19], Fig. 1) as an EMA component significantly improves the fit quality [7,10,11,20,21]. The component pc-Si is used for modelling the enhanced absorption at the boundaries of the nanocrystals.…”

Section: Methodsmentioning

confidence: 99%

Optical models for the ellipsometric characterisation of porous silicon structures

Petrik

Vázsonyi

Fried

et al. 2005

phys. stat. sol. (c)

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Thick porous silicon layers were prepared by electrochemical etching on n-and p-type single-crystalline silicon substrate, and characterised by spectroscopic ellipsometry and complementary techniques. The layers were thicker than the penetration depth of light for all wavelengths, so the samples were assumed to be bulk porous material. Best fit was obtained using two-layer models taking into account the surface inhomogeneity. The microstructure of the porous material was characterised using effective medium models with dielectric function reference spectra from the literature or calculated by model dielectric functions (MDF). Using the MDF model, reference dielectric function spectra were generated with different broadening parameters. A good agreement was found between the porosity obtained by ellipsometry and Brillouin scattering.

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Characterization of different porous silicon structures by spectroscopic ellipsometry

Cited by 54 publications

References 8 publications

Porosity and thickness characterization of porous Si and oxidized porous Si layers – An ultraviolet–visible–mid infrared ellipsometry study

Porosity and thickness characterization of porous Si and oxidized porous Si layers – An ultraviolet–visible–mid infrared ellipsometry study

Evaluation strategies for multi-layer, multi-material ellipsometric measurements

Optical models for the ellipsometric characterisation of porous silicon structures

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