Article |
Dissociative adsorption of methyl chloride on Si(001) studied by scanning tunneling microscopy
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
* To whom correspondence should be addressed. E-mail: okada{at}chem.sci.osaka-u.ac.jp
Abstract
Chemical reactions of methyl chloride (CH3Cl) on a clean Si(001) surface at
300 K are studied by means of scanning tunneling microscopy (STM) under ultra-high-vacuum conditions. The features appearing in the STM images are identified with the possible products of dissociated CH3 and Cl, and their distribution is also evaluated as well as the development of their distribution with increasing CH3Cl doses. The amount of Cl atoms found on the surface is approximately twice as large as that of the CH3 molecules. This leads to the conclusion that dissociative adsorption of CH3Cl on Si occurs in different processes: CH3Cl(precursor)
CH3(ad) + Cl(ad) and CH3Cl(precursor)
CH3(gas) + Cl(ad).
Keywords methyl chloride, Si(001), dissociative adsorption, STM, molecular beam
Received 23 July 2004, accepted 15 October 2004