High concentration erbium doping of silicon-rich SiO 2 thin films on silicon

Abstract

In this work, high concentration erbium doping in silicon-rich SiO 2 thin films is demonstrated. Si plus Er dual-implanted thermal SiO 2 thin films on Si substrates have been fabricated by using a new method, the metal vapor vacuum arc ion source implantation with relatively low ion energy, strong flux and very high dose. X-Ray photoelectron spectroscopy measurement shows that very high Er concentrations on the surfaces of the samples, corresponding to ∼10 at.% or the doping level of ∼10 21 atoms cm −3, are achieved. This value is much higher than that obtained by using other fabrication methods such as the high-energy ion implantation and molecular beam epitaxy. Reflective high-energy electron diffraction, atomic force microscopy and cross-section high-resolution transmission electron microscopy observations show that the excess Si atoms in SiO 2 matrix accumulate to form Si clusters and then crystallize gradually into Si nanoparticles embedded in SiO 2 films during dual-ion implantation followed by rapid thermal annealing. Er segregation and precipitates are not formed. Photoluminescence at the wavelength of 1.54 μm exhibits very weak temperature dependence due to the introduction of Si nanocrystals into the SiO 2 matrix. The 1.54-μm light emission signals from annealed samples decrease by less than a factor of 2 when the measuring temperature increases from 77 K to room temperature.