Oxygen ions are implanted into BiFeO3 films on LaNiO3/SrTiO3(1 0 0) substrates. The evolution of films is characterized by x-ray diffraction, scanning electron microscopy and cross-sectional transmission electron microscopy. The leakage current density of the implanted films is lowered by two orders of magnitude in comparison with unimplanted BFO films. The mechanisms for reduced leakage current in BiFeO3 thin films are discussed.
Zinc oxide single-crystal films are prepared by the oxidation of zinc-implanted sapphire at 700 °C for 2 h in oxygen ambient. The cross-section transmission electron microscopy image and the selected-area electron diffraction (SAED) pattern show that ZnO single-crystal films are formed on the surface of the zinc-implanted sapphire substrate. The quality and excitonic properties of the single-crystal ZnO films are studied through absorption spectra, the photoluminescence spectra and resonant Raman spectrum. The mechanisms for the formation of single-crystal ZnO films are discussed.
We report the formation of embedded ZnO quantum dots (QDs) by Zn and F ion sequential implantation and subsequent annealing. Optical absorption and photoluminescence spectrum measurements, transmission electron microscopy bright field images and selected area electron diffraction patterns indicate that ZnO QDs were formed after annealing in air or vacuum at temperatures higher than 500 °C. Atomic force microscopy images show a comparatively flat surface of the annealed samples, which indicates that only very few Zn atoms are evaporated to the surfaces. The formation of ZnO QDs during the thermal annealing can be attributed to the direct oxidization of Zn nanoparticles by the oxygen molecules in the substrate produced during the implantation of F ions. The quality of ZnO QDs increases with the increase of annealing temperature.
We report on the fabrication of hollow and sandwiched nanoparticles by ion irradiation. Ag nanoparticles embedded in silica were irradiated by N+, Si+, Ar+, and Cu+ ions at 300keV to a fluence of 5×1016ions∕cm2, by Cu+ ions at varying energies from 110to500keV to a fluence of 5×1016ions∕cm2, and by Cu+ ions at 400keV to fluences varied from 1×1016to1×1017ions∕cm2. The size of the irradiation-induced nanovoids increases with increasing ion mass and energy. The formation of nanovoids depends on the electronic and nuclear energy loss of the irradiation ions. The formation of irradiation-induced sandwiched nanoparticles is because of the capture of knocked-out Ag atoms from nanoshells by nanovoids. The size of the inner nanoparticles within the sandwiched structure increases with increasing fluence.
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