Surface reconstruction and lattice dynamics of hydrogenated Si(001):2×1

Abstract

We present a realistic calculation of the equilibrium surface structure and vibrational excitations of the hydrogenated Si(001):2×1 surface. We study a saturation monohydride coverage which is found to produce a (2×1) surface of symmetric dimers. A variety of interesting surface vibrational modes is found and discussed for this surface including a band of high-frequency vibrations associated with fivefold rings formed by the surface reconstruction. The relation between surface structure and surface vibrational modes is further elucidated by comparison with similar vibrational modes found on clean reconstructed Si(001):2×1. The results for Si-H bond bending and stretching frequencies agree with experimentally measured values for this surface.