REACTION OF METHANOL WITH POROUS SILICON

The reaction of both porous silicon and hydrogen covered (passivated) porous silicon with methanol was investigated. Adsorption of methanol onto porous silicon at 300 K resulted in cleavage of the O-H bond and formation of Si-OCH3 and Si-H surface species. Heating of these surface species to similar to 500 K caused breakage of both the C-O and C-H bonds. This resulted in the formation of Si-H surface species and the incorporation of oxygen and carbon into the porous silicon layer. Attempts to adsorb methanol onto passivated porous silicon proved unsuccessful until removal of the Si-H surface species commenced at 600 K. In addition to oxygen and carbon incorporation, Si-OCH3, Si-CH3, and Si-H surface species were observed when excess CH3OH(g) was used to drive the decomposition reaction. The stability of the Si-CH3 species when excess CH3OH(g) was present is likely due to oxygen and/or carbon passivation of the silicon surface.