Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 89: Surface Dynamics II

O 89.10: Talk

Friday, March 15, 2013, 12:45–13:00, H33

Comparison of the electronic surface states of Si(100) and Ge(100) studied by 2PPE — Kristof Zielke, •Jens Kopprasch, Christian Eickhoff, Cornelius Gahl, and Martin Weinelt — Fachbereich Physik der Freien Universität Berlin, Arnimallee 14, 14195 Berlin, Germany

We have investigated the electronic surface states at the (100)-surfaces of Si and Ge, two of the most important semiconductor surfaces in the device industry. Si(100) and Ge(100) are ideal for a comparison, because they have the same crystal structure and surface reconstruction, but exhibit distinct bulk band structures. We discuss the binding energy, the dispersion and the lifetimes of the dangling-bond states and the image-potential resonances on both surfaces and address the excitation of these surface states and their coupling to valence and conduction band continua. Furthermore, we show that the decay of photo-excited electrons in the conduction band is significantly influenced by the surfaces states. In particular, we discuss the role of inter- and intraband electron-phonon scattering between the conduction band and the unoccupied surface state D_down, and back scattering to the valence band. Thereby we found significant differences in the timescale of the decay processes on Si and Ge.