Si nanocrystals in SiO2 films analyzed by small angle X-ray scattering

Amorphous SiO/SiO₂ multilayers were studied using grazing-incidence small-angle X-ray scattering (GISAXS). Such SiO/SiO₂ superlattices were prepared by alternately magnetron sputtering of 3 nm thin films of SiO and 3 nm of SiO₂ (10 layers each) on Si (100) substrate. Rotation of the Si substrate during evaporation ensures the homogeneity of the films over the whole substrate. After evaporation the samples were annealed at 1050 °C for 2 h in vacuum or in air. The analysis of the 2D GISAXS pattern has shown that Si nanocrystals are formed in the annealed samples. Using a Guinier approximation, the inter-nanocrystal distance (10.5 nm) and radius of gyration (2.3 nm) have been obtained for the samples annealed in vacuum. Samples annealed in air have shown similar peak values which were however, much wider distributed.