Ivan Ohlídal, Milan Líbezný
Immersion ellipsometry of semiconductor surfaces
Surface and Interface Analysis 16 (1990) 46–53
In this paper, three methods of immersion ellipsometry based on measuring the ellipsometric parameters in air and non-absorbing liquids are used for analysing silicon, germanium and gallium arsenide single crystals covered with very thin native oxide layers under normal laboratory conditions. If the values of the extinction coefficients of the semiconductors are known with sufficient accuracy, the values of the refractive indices of these semiconductors and the thicknesses and the refractive indices of the effective surface layers can be determined with satisfactory or high accuracy (the effective layer represents a double layer consisting of the native layer and the interface layer). If the values of the optical parameters characterizing the interface layer between the silicon substrate and its native oxide layer are known, the values of both the thickness and the refractive index of the native oxide layer can be determined. The values of all the optical parameters (including the extinction coefficient) of the system formed by a silicon surface covered with the native oxide layer can be determined with good accuracy if the experimental data corrresponding to this system are interpreted together with those corresponding to a silicon surface covered with a thick SiO2 (amorphous) film. This procedure can be used if the values of the optical parameters of the interface layer are known in a reliable way. The methods are applied at a wavelength of 632.8 nm.
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Citing Articles
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