X-ray and infrared spectroscopy of layers produced by cosputtering of spatially separated SiO₂ and Si sources

Ultrasoft X-ray emission spectroscopy and infrared spectroscopy are used to study the Si/SiO₂ composite structure produced by deposition from the Si and SiO₂ sources onto the Si substrate. Separation of the sources by a rather long distance (96 mm) made it possible to vary the composition of the layer along the direction parallel to the sample surface in a wide range from almost pure SiO₂ to Si. On the basis of the X-ray emission Si L_{2, 3} spectra, amorphous silicon a-Si and silicon oxide SiO₂ were identified in the layers. The infrared spectra show that there are Si nanocrystals in the layers. Variations in the content of Si/SiO₂ along the direction parallel to the wafer surface are established. The data obtained by the above-mentioned techniques are correlated with the results of calculations of the layer composition and with the data of profilometric measurements of the layer thicknesses.