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

► Ag growth proceeds in a layer-by-layer mode on Bi/Ag(111)√3 × √3 substrates. ► The top surfaces of the Ag layers were always covered by a √3 × √3 reconstruction. ► The electronic structure of the top surface was identical to that of the Bi/Ag(111)√3 × √3. ► Bi atoms at the substrates acted as surfactant in the growth of Ag layers.