Theoretical study on hydrogen reaction processes on H/Si(0 0 1) surface

The reaction processes of an incident H atom with the H- or D-terminated Si(0 0 1)-(2 1) surface are theoretically investigated by using first-principles molecular dynamics simulations. Because the atomic hydrogen reaction process producing an H2 (HD) molecule is exothermic, this reaction is considered to be observed in many cases. It is found that an H2 (HD) molecule is produced in all of the cases treated in this study. The final kinetic energy of the resultant H2 (HD) molecule is found to be mostly distributed to the vibrational energy, whereas the translational energy of the resultant molecule is estimated to be relatively low. In this reaction process, a resultant H2 (HD) molecule is weakly trapped into a bound state site between two Si dimer rows on the surface followed by the desorption from the surface. This type of reaction processes corresponds to the direct abstraction of Eley-Rideal mechanism, which is in good agreement with the previous experimental results