Ge dots embedded in SiO2 obtained by oxidation of Si/Ge/Si nanostructures

Selective epitaxial growth was used to fabricate narrow Si/Ge/Si pillar nanostructures in small holes in ultrathin oxide (UTO) on Si(100). The self-assembled holes with diameters of 5-30 nm were obtained by in situ partial removal of the UTO at high temperature. The UTO formation and the annealing process were optimized for a high density of holes. The SiGe nanopillars were grown with sizes determined by the initial hole diameter in the UTO. Crystalline Ge dots embedded in oxide were formed by oxidation of the pillar nanostructures. High-resolution transmission electron microscopy (HRTEM) was used to study the pillar nanostructures and the dot shapes before and after oxidation. Capacitors obtained with the oxidized samples showed a hysteresis in their C-V curves attributed to charge retention in the Ge dots embedded in the oxide.