Dresden 2006 – scientific programme
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HL: Halbleiterphysik
HL 3: III-V semiconductors I
HL 3.8: Talk
Monday, March 27, 2006, 12:00–12:15, POT 51
Structure and scanning tunneling microscopy images of Auadsorbed on GaAs(111)B-(√3 × √3)-R30∘ — •Hongsuk Yi1, Peter Kratzer1, Emelie Hilner2, Anders Mikkelsen2, and Edwin Lundgren2 — 1Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195Berlin, Germany — 2Institute of Physics, LundUniversity, Box 118, SE-22100 Lund, Sweden
Adsorption of gold on GaAs surfaces is interesting both for metallic contacts and for "catalyzing" growth of GaAs nanorods. Recently, it has been observed that small amounts of Au induce a well-ordered (√3×√3) reconstruction on the GaAs(111)B surface, replacing the (2 × 2) As-trimer structure of the clean surface. We investigate the stable adsorption sites and simulate scanning tunneling microscopy (STM) images of Au absorbed on the GaAs(111)B surface, using the GGA approximation of density functional theory, and plane-wave/pseudopotential calculations.
We propose an energetically favorable model for the Au/GaAs(111)B-(√3 × √3) surface with one Au per unit cell located in a threefold hollow site. From the calculated potential energy surface we obtain a diffusion barrier height of 0.45 eV for Au adatoms. In the simulated filled-state STM images the Au atoms appear as triangular structures whose edges point towards neighboring As atoms. The proposed structural model is in agreement with experimental data from low-energy electron diffraction and STM.