The peculiarities of Si/SiO2 interfaces in the Si–SiO2 systems with Si nanocrystals

Si-rich-SiO2 layers with excess silicon of 45–50% were grown by RF magnetron co-sputtering from pure SiO2 and Si targets and were studied by Raman scattering, HRTEM, electron-paramagnetic resonance and X-ray diffraction (XRD) methods as well as by photo-voltage technique operated at different temperatures. The effect of Si substrate orientation of (1 1 1) or (1 0 0) on the layers properties was investigated. It was shown that high-temperature annealing in inert atmosphere stimulates a formation of Si crystallites in the film volume and of quartz crystallites near the layer/substrate interface. The dependences of the space orientation and the total volume of the formed quartz crystallites on substrate orientation were observed. The concentration of quartz crystallites in the films grown on the (1 0 0) Si substrate was found to be higher in several times than that in the films grown on the (1 1 1) Si substrate. The effect of the mechanical stresses on the layer–substrate interface states was observed for the layer prepared on the (1 1 1) Si substrate. It was shown that the natural oxidation of the layers before the annealing at high-temperature results in an increase of the positive fixed charge in the layer. At the same time it was found the formation of EX-centers containing Si vacancies close to crystallite/matrix interface.