Silicon aggregates produced by laser beam in a silicon carbide surface

Silicon carbide is a material with potential for the fabrication of composites and coatings in sensitive organs of space vectors and vessels. We have examined the effect of a laser shot on a silicon carbide coating deposited on graphite substrate. Micro-Raman spectroscopy was revealed to be a very suitable tool for the study of the structure evolution, physically as well as chemically. We have shown that silicon carbide completely disappeared while silicon was formed. The study of laser shots onto samples placed under controlled atmospheres, containing variable pressures of oxygen and nitrogen, allows a mechanism of carbon departure to be deduced. The formation of silicon dimers, trimers and tetramers in silicon carbide matrix, was also seen dependending on the laser power reaching the target. These species have specific spectral characteristics which are shown to be quite different from that of bulk silicon.