Atomic transport in insulators under high-flux heavy-ion implantation

Although ion implantation has a unique merit in fabricating immiscible metal–insulator composites being promising for non-linear optical applications, high-flux implantation especially is subject to pronounced atomic transports, either inside or outside the solid. Negative Cu ions of 60 keV irradiated substrates of a-SiO 2 and MgO · 2.4(Al 2 O 3 ) at fluxes up to 100 μA/cm 2 . Atomic redistribution of Cu nanoparticles inside the substrate was observed by cross-sectional TEM. Atomic release of Cu implants out of the substrate was detected by ion-induced photon spectroscopy, with fast-response CCD cameras. Spontaneous metal precipitation in insulators is attained at high flux. The ion-induced photon spectra of a-SiO 2 consist of sharp line spectra and a broad luminescence. The presence of line spectra demonstrated the outward transport into vacuum and loss of Cu atoms via the surface to the vacuum. Cations in MgO · 2.4(Al 2 O 3 ) are also significantly released to the vacuum via the surface. The outward mass transport results from ion-induced sputtering/sublimation of implants, concurrently with radiation-induced diffusion towards the surface.