ADSORPTION OF ETHYLENE ON THE SI(100)-(2X1) SURFACE

The adsorption of ethylene on Si(100)-(2 x 1) has been studied using high-resolution electron energy loss spectroscopy. Upon adsorption, the ethylene molecule rehybridizes from sp2 to sp3 and forms a di-sigma bonded structure to the surface. However, the bonding of the surface silicon atoms - whether or not the Si-Si dimer bond remains - cannot be derived from just a study of ethylene adsorption. With low exposures of atomic hydrogen on the ethylene-saturated Si(100) surface, we observed an additional Si-H vibrational mode and no significant change in the chemisorbed ethylene spectrum. This result leads to the conclusion that the surface dangling bonds still exist after ethylene adsorption, and they are accessible to atomic hydrogen. Consequently, the adsorption of ethylene must be accompanied by cleavage of the original Si-Si dimer bonds on the surface.