The decomposition of alkyl silanes (SiMe sub n H sub (4-n), 0<=n<=4) on Ni(100).

While the adsorption of hydrocarbons on a wide variety of transition metals is a well studied area of surface science, very little is known about the reactions of alkyl silanes on these same surfaces. In the present study we use primarily temperature programmed desorption and Auger electron spectroscopy to follow the low temperature adsorption and subsequent decomposition of a complete series of alkyl substituted silanes of the formula SiMe sub n H sub (4-n) (0=n=4) as well as Si sub 2 Me sub 6. The effects of increasing methyl substitution are dramatic; for n=3 substantial decomposition is observed while for both tetramethylsilane and hexamethyldisilane desorption is predominantly molecular. The extent of decomposition and the maximum desorption temperature of the resulting fragments are strongly determined by the concentration of steps and/or other defects on the surface as well as the presence of carbon and silicon impurities.