VIBRATIONAL-ENERGY RELAXATION DYNAMICS OF SI-H STRETCHING MODES ON STEPPED H/SI(111) 1X1 SURFACES

The vibrational energy relaxation rates of excited Si-H stretching modes on the monohydride step of miscut H/Si(111) 1 x 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-Paninello ab initio MD method. The calculated Si-Si-H bending frequencies and relaxed structures are then used to refine the empirical potential for the classical MD simulations. The lifetime of the excited Si-H 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 degrees monohydride stepped surface. The vibrational relaxation rate of the Si-H stretching modes on the 15 degrees monohydride stepped surface are also calculated and predicted to have a slightly shorter lifetime than for the 9 degrees surface.