Spectroscopy of positively and negatively buckled domains on Si(111)-2x1

The influence of the buckling type of the Si(111)-2 x 1 surface on the electronic structure is studied with high-resolution scanning tunneling microscopy and scanning tunneling spectroscopy and compared to ab initio calculations. We utilize the multitude of domain boundaries to identify differently buckled domains. I (V) measurements with high spatial and energetic resolution show the electronic structures of the two buckling types. We determine the position of the surface bands in the band gap of the bulk silicon and relative to each other. The high spatial resolution provides insight into the crossover from one buckling type to the other at the domain boundaries.