Electronic structure of alkali/Si(111):B semiconducting interfaces

We have evidenced by LEED and STM a novel $2\sqrt{3} \times 2\sqrt{3}$ surface reconstruction for K, Rb and Cs on Si(111):B.\footnote{L. A. Cardenas et al, Phys. Rev. lett. 103, 046804 (2009)} The $2\sqrt{3}$ charge ordering occurring mainly in Si dangling bonds has been evidenced by high resolution photoemission measurements on core levels whereas the k-dependent photoemission spectral function agrees with the $2\sqrt{3}$ symmetry establishing a full gap higher than 1 eV.\footnote{C. Tournier-Colletta et al., Phys. Rev. B 82, 165429 (2010)} These results will be discussed in the light of ab initio calculations giving evidence for strong atomic distortions associated with a possible full charge ordering in dangling bonds, in connection to a large energy gap,\footnote{ L. Chaput et al., to be published} which is compatible with a bi-polaronic scenario.