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 mod es on the monohydride step of miscut H/Si(111) 1 x 1 surfaces are calc ulated using Bloch-Redfield theory combined with classical molecular d ynamics (MD) simulation. The structure and vibrational frequencies of the surface are first investigated using the Car-Paninello ab initio M D method. The calculated Si-Si-H bending frequencies and relaxed struc tures are then used to refine the empirical potential for the classica l 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 th e magnitude and the trend of the calculated results agree well with th e experimental measurement on the 9 degrees monohydride stepped surfac e. The vibrational relaxation rate of the Si-H stretching modes on the 15 degrees monohydride stepped surface are also calculated and predic ted to have a slightly shorter lifetime than for the 9 degrees surface .