Bi induced step-flow growth in the homoepitaxial growth of Au(1 1 1)

Homoepitaxial growth of Au on Bi-covered Au(1 1 1) was studied at room temperature using reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES). From observations of RHEED it is found that the Au(1 1 1) (23 1) reconstruction structure changes to a (1 1) by about 0.16–0.5 ML deposition of Bi and to a (2H3 2H3)R308 by about 1.0 ML deposition of Bi, respectively. The surface morphology evolution by Bi deposition leads to a change of Au homoepitaxial growth behavior from layer-by-layer to step flow. This indicates that the surface diffusion distance of Au atoms on the Bi-precovered (1 1) and (2H3 2H3)R308 surfaces is longer than that on the Au(1 1 1) (23 1) clean surfaces. A strong surface segregation of Bi was found at top of surface. It is concluded that Bi atoms acted as an effective surfactant in the Au homoepitaxial growth by promoting Au intralayer mass transport.