Surface-directed spinodal decomposition in the pseudobinary alloy (HfO2)x(SiO2)1 12x

Hf silicate films (HfO2)0.25(SiO2)0.75 with thicknesses in the range 4\u201320 nm were grown on silicon substrate by atomic layer deposition at 350 \ub0C. Hf distributions in as-grown and 800 \ub0C annealed films were investigated by high resolution transmission electron microscopy (HRTEM), angle-resolved x-ray photoelectron spectroscopy (ARXPS), and medium energy ion scattering (MEIS). HRTEM images show a layered structure in films thinner than 8 nm. The ARXPS data also reveal a nonuniform distribution of Hf throughout the film depth. Diffusion of SiO2 to the film surface after a longer time anneal was observed by MEIS. All these observations provide evidence for surface-directed spinodal decomposition in the pseudobinary (HfO2)x(SiO2)1 12x alloy system.Peer reviewed: YesNRC publication: Ye