Structural analysis of annealed amorphous SiO/SiO2 superlattice

We present a study on amorphous SiO/SiO2 superlattice prepared by high vacuum physical vapor deposition of 4 nm thin films of SiO and SiO2 (10 layers each) from corresponding targets on silicon substrate. After evaporation the samples were annealed at different temperatures in the 600 °C to 1100 °C range.The analysis of the 2D grazing-incidence small-angle X-ray scattering pattern has shown the existence of a clear Bragg peak due to the bilayer correlation in vertical direction. It is shown that annealing linearly reduces the thickness of the bilayer up to 1100 °C when the conversion to the SiO2 phase is completed. The particles formed at that temperature are not completely spherical and their vertical correlation is maintained only partly. We attribute this bahavior to a not optimal control of the silicon diffusion within the ex SiO layer.