Structural properties of granular Bi-SiOx films prepared by low-energy cluster beam deposition

In this paper, we propose a new technique for the elaboration of size controlled nanoparticles embedded in a matrix: the low-energy cluster beam deposition (LECBD). Bi-SiO x nanocermets have been prepared by codeposition of Bi neutral clusters and SiO x molecules. We present a study by transmission electron microscopy (TEM) of the structural properties of these new cermets. The clusters are generated by the gas-aggregation technique in a thermal source which produces clusters with a low energy. Then, the incident clusters do not break at the impact on the surface and conserve their size and structure. Consequently, the cermets are composed of Bi nanograins with a size distribution comparable to that of the free clusters, at low metallic concentrations. This result has been obtained for three different size distributions of the free clusters showing that the LECBD technique allows the control of the size of the embedded particles in the nanometric range. Moreover, the size and the concentration of grains are independent at metallic concentrations below 10%. This result is very important for studying the influence of these two parameters on the physical properties of granular materials.