Initial stage of Ag growth on Bi/Ag(111)√3 × √3 surfaces

We investigated the initial stage of Ag growth on Bi/Ag(111)√3 × √3 substrates at room temperature. The nucleation of small one-monolayer-high islands on the substrates was observed by scanning tunneling microscopy (STM). The islands extended laterally and coalesced to form a continuous layer with further deposition. The growth proceeded in a layer-by-layer mode via the repeated nucleation and coalescence of monolayer islands. The top surfaces were always covered by a √3 × √3 reconstruction during this growth. dI/dV images and scanning tunneling spectra (STS) revealed that the electronic structure of the grown surfaces was identical to that of the Bi/Ag(111)√3 × √3 substrate surfaces. The surfactant action of the Bi atoms reasonably explains the layer-by-layer growth of Ag films with a √3 × √3 surface reconstruction.