Three-dimensional deposition of silicon from silicate glass with dispersed metallic aluminum by a femtosecond laser

Abstract

We have fabricated silicon structure in silicate glass prepared with metallic aluminum in the starting material, using femtosecond laser irradiation and subsequent annealing. Small Si-rich structures such as oxygen-deficiency (O-deficiency) defects or Si clusters transform into nano-sized Si particles by the focusing irradiation of the laser. Then the Si-rich structures grow into micro-size particles due to the thermite reaction promoted by heat treatment. We determine the effect of focused laser pulse on the Si deposition process by using a time-resolved transient lens method with a sub-picosecond laser pulse. Localized high-temperature, high-pressure, and the generation of shock waves appear to be very important in forming the Si-rich structures that ultimately grow into Si particles. The diffusion of oxygen by shock waves and the existence of Al-rich structures help form Si-rich structures as Si-O bonds continuously break under high temperature. The focusing irradiation of femtosecond lasers is very useful for fabricating Si structures inside glass.