Keywords: iron nanoparticles, ion implantation, XANES, XPS, RBS, nanotechnology, structural changes, chemical changes, Fe nanoparticles, SiO2, silicon dioxide, silica, sputtering
Structural and chemical changes during the growth of Fe nanoparticles in SiO2 under low energy ion implantation
Low energy (15 keV) Fe implantation into SiO2 (400 nm) on Si initially leads to the formation of very small Fe nanoparticles. The Fe nanoparticles grow in size and remain crystalline as the fluence is increased. At the same time there is Si and oxygen sputtering that reduces the thickness of the SiO2 layer. It is this sputtering that leads to Fe nanoparticles that protrude from the surface for high Fe fluences of at least 5 × 1016 at.cm−2. The surface nanoparticles develop an oxide layer when exposed to air. Fe silicides (probably FeSi2) also occur for these high fluences. Their formation is likely to occur because sputtering leads to a Si excess near the surface.