Vibrational energy relaxation dynamics of SiH stretching modes on stepped H/Si(111) 1×1 surfaces

The vibrational energy relaxation rates of excited SiH stretching modes on the monohydride steps of miscut H/Si(111) 1×1 surfaces are calculated using Bloch-Redfield theory combined with classical molecular dynamics (MD) simulation. The structure and vibrational frequencies of the surface are first investigated using the Car-Parrinello ab initio MD method. The calculated SiSiH bending frequencies and relaxed structures are then used to refine the empirical potential for the classical MD simulations. The lifetime of the excited SiH stretching mode at the step is found to be shorter than the modes on the terrace. Both the magnitude and the trend of the calculated results agree well with the experimental measurement on the 9° monohydride stepped surface. The vibrational relaxation rate of the SiH stretching modes on the 15° monohydride stepped surface are also calculated and predicted to have a slightly shorter lifetime than for the 9° surface.