Ag on Mo(110) studied by AES and STM

Auger electron spectroscopy (AES) and scanning tunnelling microscopy (STM) have been used to investigate the growth behaviour of ultra-thin Ag films on a Mo(110) surface at room temperature. An analysis of AES and STM measurements indicates that three-dimensional (3D) growth of a Ag film is observed. For submonolayer coverage, the growth of Ag is mediated by a two-dimensional step-flow mechanism. During the initial stage of this growth, the first Ag layer nucleates and creates islands (average size of islands is about 180 ± 20 nm²) at Mo step edges. In the monolayer coverage range, the decoration of substrate steps by Ag can be distinguished by the presence of a fractional step of p₁ = 0.86 ± 0.6 Å height at the Ag–Mo boundary. As the sample is post-annealed to 700 K, the morphology of the surface changes. Step-flow growth in this case gives rise to a regular Ag nanostripe network attached to Mo(110) step edges. The corrugation profiles reveal the protrusion of silver nanostripes of thicknesses p₁ = 0.98 ± 0.16 Å and p₂ = 0.39 ± 0.06 Å for submonolayer and monolayer coverage ranges, respectively, above each single step of a Mo terrace morphology.