A GISAXS study of SiO/SiO2 superlattice

We present a study on amorphous SiO/SiO2 superlattice using grazing-incidence small-angle X-ray scattering (GISAXS). Amorphous SiO/SiO2 superlattices were prepared by high vacuum evaporation of 3 nm thin films of SiO and SiO2 (10 layers each) on Si (100) substrate. Rotation of the Si substrate during evaporation ensures homogeneity of the films over the whole substrate. After evaporation samples were annealed at 1050 or 1100 °C for 1 h in vacuum. The analysis of the 2D GISAXS pattern has shown that Si nanocrystals are present in the annealed samples. From the 2D GISAXS pattern it is possible to determine the shape, size and inter-particle distance. Using a Guinier approximation, their inter-nanocrystal distance (5 nm) and radius of gyration (1.5 nm) have been obtained. Such nanostructured material might be of great interest for photovoltaic conversion.