Fabrication of photoluminescent Si-based layers by air optical breakdown near the silicon surface

A novel “dry” method for the fabrication of Si/SiOx nanostructures exhibiting strong visible photoluminescence (PL) is introduced. The method consists in the treatment of a silicon target surface by air breakdown plasma produced by a CO2 laser radiation in atmospheric air. The treatment leads to the formation of a thin porous layer on the silicon wafer, which exhibits a 1.9–2.0 eV PL. Possible mechanisms of nanostructure formation and PL origin are discussed.