Influence of charged impurities on the surface phases of Sn/Ge(1 1 1)

The √3α and 3×3 reconstructions on the Ge(1 1 1)–Sn surface have been perturbed by small amounts of iodine and potassium to test the spectral response in the course of a synchrotron radiation photoemission study. We demonstrate the inadequacy of the static model of the √3α phase at room temperature and of the surface charge density wave model of the 3×3 phase at low temperature. Instead, the influence of the charged impurities is consistently explained when considering that dynamical fluctuations in the tin adatom positions are frozen in upon passing the phase transition temperature.