Silicon nanocrystals formed by pulsed laser-induced fragmentation of electrochemically etched Si micrograins

We report on effective way to prepare luminescent silicon nanocrystals (Si-ncs) by pulsed laser-induced fragmentation of Si micrograins in spin on glass (SOG) solution at room temperature. The Si grains were prepared by pulverization of porous silicon wafers. Micrograins dispersed in SOG were fragmented by focused pulsed laser irradiation and luminescent Si-ncs of quantum confinement size were formed. Laser irradiation energy over the band gap of silicon provoked optical absorption. The resulting plasma superheat, together with strong shock waves, induced Si micrograin fragmentation into Si-ncs with visible photoluminescence. The maximum of which can vary as a function of laser fluence.