Dynamic steric effect in silicon chemistry

Hashinokuchi, Michihiro*; Okada, Michio*; Moritani, Kosuke*; Teraoka, Yuden; Kasai, Toshio*

The orientation of an incident molecule is expected to play an important role in surface chemical reactions. In order to elucidate molecular orientation (Steric) effects, we have developed a ultra-high-vacuum compatible oriented-molecular beam line and applied it to investigation of reactions on Si surface. Steric effect of CHCl/Si(001)-21 disociative adsorption was studied using the King-Wells method. It was found that the non-equilibrium surface trapping is a key of CHCl dissociative adsorption on the Si(001) surface. We present a new approach using X-ray photoelectron spectroscopy. We applied this to the NO/Si(111)-77 system. It was found that the dissociative adsorption occurs via a precursor in the incident energy region from 25 to 78 meV. Reaction probability from N-end collision is higher than that of O-end collision. This result indicates that the kinetic energy of incident NO molecules was easy to loss in the N-end collision than O-end collision.