Dynamics of the Si(100) surface

The Si(100) surface is constituted by asymmetric dimers and presents complex dynamical behaviour. To understand the influence of dimer motion on the surface electronic properties, we investigate the dynamics of the Si(100) surface experimentally and theoretically in a wide temperature range (150-1200 K). High-resolution electron energy-loss spectroscopy measurements are compared to a microscopic tight-binding calculation of the dielectric function. An instantaneous symmetric-like flat dimer configuration due to fast dimer-flipping is responsible for the electronic transition at 0.8 eV and for the surface metallization observed at 900 K, well below the suggested incomplete melting temperature (1400 K).