Figures for: Si on As-terminated Si(111)   (Click on the pictures to enlarge)

Fig.1: Energy contour for a single Si adatom above the As surfactant layer. The minima are at H3 (small full dots) and the saddle points for diffusion are at T4 (middle size full dots). The diffusion path from H3 via T4 to H3 is indicated.

Fig.2: Positions along the exchange path projected to the surface plane. Shown are the paths of the Si atom (full line) and the As atom (dotted line) involved in the reaction. The atom positions for the local minima encountered onn the path are indicated by circles (full lines for Si, dotted for As). The dashed line H3-T4-H3 is the diffusion path of the Si adatom.

Fig.3: Energy (relative to H3 position of Si adatom) along the diffusion path (to the left of x=0) and along the exchange path to substitutional Si (to the right). The atomic configurations for important minima are shown as insets: H3: Si_Ad;SM1: asymmetric dimer;Si_Sub: substitutional Si and As adatom (light: Si adatom; gray: As; black: Si bulk). [The insets can be found in the complete figure]