Formation of silicon nanocrystals in SiO2 by oxireduction reaction induced by impurity implantation and annealing

Abstract

Silicon nanocrystals are candidates for complete integration of optical and electronic functions in Si-based devices. In this work, we investigate the feasibility of producing them by a method based on impurity-induced oxireduction of SiO2. Thermodynamic calculations suggested Mg as a suitable impurity due to its chemical strength in oxireducing the SiO2 matrix and simultaneously avoiding the formation of Si-based compounds. The samples were obtained by 1×1017 Mg+/cm2 implantations into fused silica followed by thermal anneal in vacuum. Transmission electron microscopy (TEM), and Raman and photoluminescence measurements confirmed the presence of Si nanocrystals. The average nanocrystal size was evaluated according to the phonon confinement and quantum confinement models relative to the Raman and photoluminescence results, respectively, to be about 10 nm, in agreement with the TEM results.