Formation of SiGe Nanoparticles by Dry and Steam Thermal Oxidation of Thin Polycrystalline Layers

Nanoparticles embedded in a dielectric medium have been formed by dry and steam thermal oxidation at specific temperatures and process times of polycrystalline Si0.7Ge0.3 layers deposited on thermally oxidized Si substrates. We present a study of the influence of the oxidation process parameters: oxidation atmosphere, temperature and time on: a) the composition of the grown oxide, b) the Ge segregation, c) the formation of nanoparticles, their composition and size, and d) the properties of the cathodoluminescence emission of the oxidized films. Oxidation in a dry O2 atmosphere results in a full Ge segregation. The formation of Ge islands embedded in an oxide matrix is demonstrated. Ge segregation is slower in steam thermal oxidation than in dry O2. In this case Ge-rich SiGe particles are formed. In both processes, an important increase in the cathodoluminescence emission associated with the presence of Ge rich nanoparticles is obtained.