A semi-empirical study of the chemisorbed state of benzene on Si(100)-(2x1)

Abstract

The chemisorbed state of benzene on Si(100)-(2 x 1) has been studied using a cluster model and semi-empirical PM3 calculations. Starting from four different initial sites as the possible adsorption sites, the most stable structure is obtained as the adsorption at the pedestal site, where one benzene molecule interacts with two silicon dimers of the surface. This stable adsorption of benzene on the pedestal site has not been proposed previously, but is in good accord with the experimental results. The carbon atoms bonded to silicon dimers have some sp(3) characters, in accordance with the experimental results of high resolution electron energy loss spectroscopy, while the others preserve the hybridization state in a free molecule. In addition, the saturation coverage of benzene predicted from the adsorbed state is in agreement with the experimental results.