Photoluminescence spectra of laser-synthesized Si/C/N ultrafine powders

Ultrafine Si/C/N ceramic powders were synthesized by a CO2-laser-induced reaction between silane (SiH4), ammonia (NH3) and acetylene (C2H2). The powders were characterized by infrared (IR) reflection and photoluminescence (PL) spectroscopy. From the infrared reflection spectra of Si/C/N powders, we have identified the causes of the strong photoluminescence present in these powders. The photoluminescence spectra of Si/C/N powders originate from the presence of hydroxylated and amorphous silicon (a-SiO2) formed at the porous surface of these powders. We have shown that different chemical bonding between Si, C and N atoms, the degree of crystallinity of ternary powders and their porosity strongly influence the processes at their surface, i.e. the formation of amorphous silicon and silanole.