Visible photoluminescence from nanostructured Si-based layers produced by air optical breakdown on silicon

Abstract

Pulsed radiation of CO2 laser has been used to produce an optical breakdown on a silicon target in atmospheric air. After several breakdown initiations near the threshold of plasma production, a highly porous layer was formed under the radiation spot on the silicon surface. The fabricated layers presented the porosity of 75%–80% and were formed of silicon nanocrystals imbedded in SiO2 matrix. They exhibited strong photoluminescence (PL) around 2.0 eV, which was stable to a prolonged continuous illumination of samples. Possible mechanisms of nanostructure formation and PL origin are discussed.