Abstract

Silicon monoxide (SiO) and atomic silicon (Si) are potentially important intermediates in a variety of combustion and plasma environments. Examples are silicon-doped flames used in vapor-phase axial deposition for the manufacture of optical waveguides and a variety of CFD and plasma-enhanced chemical- vapor deposition processes for the deposition of silicon and silica in microelectronics fabrication. We have observed laser-induced-fluorescence (LIF) from SiO in low-pressure glow discharges in Ar/O₂/SiCl₄ mixtures and in atmospheric-pressure CH₄/O₂ flames doped with SiCl₄. Fluorescence was excited by means of the A¹π-X¹E⁺ transition at approximately 230 nm. Spectra were assigned by comparison with simulated spectra computed from previously reported line positions and rotational and vibrational temperatures were obtained. Measurements of resolved fluorescence with a gated optical multichannel analyzer were used to determine energy transfer rates in the A¹π state. Si atoms were observed in low-pressure discharges and also as a product in the 193 and 251 nm multiphoton dissociation of silanes. Si atoms were monitored through LIF by scanning the laser across the 4s ³P⁰→3_p²³P transition at approximately 250 nm and monitoring the undispersed fluorescence. Production of Si 4s ³P⁰ in the 193 and 251 nm multiphoton dissociation of silanes was also observed, and its implications for Si atom diagnostics will be discussed.

© 1990 Optical Society of America