Adsorption of S on Si(111) with M-4 x 4 superstructure


TAYRAN C. , ÇAKMAK M. , Srivastava G. P.

SURFACE SCIENCE, vol.701, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 701
  • Publication Date: 2020
  • Doi Number: 10.1016/j.susc.2020.121694
  • Title of Journal : SURFACE SCIENCE

Abstract

The atomic and electronic structures are calculated for the M-4 x 4 superstructure of S/Si(111), which was recently identified by Schmidt et al. [Surf. Sci.694 (2020) 121561] by using the spot profile analysis low-energy electron diffraction (SPALEED) and confirmed by scanning tunneling microscopy (STM). The electronic band structures are found to be semiconducting in nature for three different S structures: monomer, Dimer-A and Dimer-B, each of which saturates all the Si dangling bonds. Due to the varying numbers of S atoms per unit cell, we have calculated the lowest energy phase in the accessible S chemical potential range. Dimer-A and Dimer-B are the lower energy phase and their accessible chemical potential value is less than the monomer case, in excellent agreement with the results of Schmidt et al. Dimer-B is slightly more stable geometry than Dimer-A. Application of the nudged elastic band (NEB) method suggests that there is a rotational activation barrier of 40 meV along the Dimer-A-Dimer-B reaction path.