Formation of Zn–ZnO core–shell nanoclusters by Zn/F sequential ion implantation

Zn nanoclusters were formed in highly-pure amorphous silica slices by 160 keV Zn ions implantation with a dose of 2 x 10(17) ions cm(-2). The Zn implanted sample was then implanted with F ions at 40 keV with 2 x 10(17) ions cm(-2). TEM and HRTEM studies indicate some core-shell nanoclusters have been formed in the Zn/F sequentially implanted sample. An extended x-ray absorption fine structure spectrum of the Zn/F sequentially implanted sample shows the existence of both Zn and ZnO. The oxygen atoms in the substrate are replaced by implanted F ions, producing 02 molecules, which partially oxidize the already formed Zn nanoclusters and form ZnO nanoshells. A bond length contraction of ZnO and Zn nanoclusters with different sizes was observed, which can be explained by the surface tension of nanoclusters and the compression stress from surrounding substrate effects. The latter was confirmed by the Fourier transform infrared attenuated total reflection spectra.