Formation and structure of Sn and Sb nanoclusters in thin SiO 2 films

Abstract

We investigated the formation mechanism of Sn and Sb nanoclusters in thin SiO 2 films by X-ray absorption spectroscopy (XAS). Sn and Sb nanoclusters have been formed in 85 and 22 nm thick SiO 2 layers, respectively, by 80 keV/1×10 16 cm −2 Sn and 10 keV/5×10 15 cm −2 Sb ion implantation followed by thermal treatments. XAS analyses provided unique information on the local environment of Sn and Sb ions in SiO 2 with respect to different annealing conditions. Sn and Sb atoms are mainly coordinated with oxygen in the as-implanted samples. Annealing at different temperatures (800–1100 °C) and in different atmospheres (N 2 or Ar+7%H 2) leads to the formation of metallic clusters or oxidized ones. Even when the metallic phase is detected, a fraction of Sn or Sb atoms still remains dissolved in the matrix or forms small oxide clusters. Annealings at high temperature (1100 °C) for a short time (30 s) or in Ar+7%H 2 atmosphere (even if at lower temperature) are more effective for the formation of metallic clusters and for reducing the oxidized atom percentage in the matrix.