The thermal conductivity of as prepared and oxidized porous silicon layers was estimated by means of micro-Raman Spectroscopy. The shift in peak position of the Raman Stokes spectra from the same sample spot obtained at two different values of the laser beam power was used in this respect. This shift is due to local temperature increase by increasing the laser power. The sample temperature for a given laser power was estimated in two ways. a) from the temperature dependence of the Raman Stokes frequency, and b) from the intensity ratio of the Raman Stokes to Raman Antistokes peaks. Raman spectra from oxidized porous silicon layers exhibited lower frequencies and they were broader than those from the as-prepared layers due to the presence of smaller crystallites within the material. The thermal conductivity decreased by increasing the oxidation temperature. In oxidized samples, it was almost one order of magnitude smaller than in the as-prepared material. Depth profiling did not show any significant changes of thermal conductivity across the porous layer.
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