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Surface morphology of size-selected silver nanocluster films grown by dc magnetron sputtering has been investigated by means of an atomic force microscopy (AFM). From the height-height correlation functions ( HHCF) obtained from corresponding AFM images, the scaling exponents are calculated and two types of growth regimes have been observed. In the first regime, the growth exponent is found to be β 1 = 0.27 ± 0.07 close to the KPZ growth exponent, while in the second growth regime shadowing effect plays dominant role which gives the growth exponent value β 2 = 0.88 ± 0.28. On the other hand for the whole deposition regime, the roughness exponent value is found to be constant around α = 0.76 ± 0.02. UV-vis spectroscopy measurement suggests how the average reflectance of the film surface changes with different growth times. Virgin Si(100) 7 min Surface normal 45 0 Cluster beam 20 min arXiv:1911.09381v1 [cond-mat.mtrl-sci]

In this paper, we describe a novel method of synthesis of bimetallic Ag–Au alloy nanoparticles with an estimated Ag to Au concentration ratio of ∼3:1 by using a gas-aggregation cluster source. The real time chemical changes occurred on the surface of the alloy film during different stages of annealing at an elevated temperature are observed by in-situ x-ray photoelectron spectroscopy analysis. It is found that the concentration of both Ag and Au of the alloy film simultaneously decreases with the increase of the annealing time. The chemical states of the elements present on the surface are analyzed from the HR-XPS data, which are recorded for the dominant elements present on the surface. From the analyses, it is found that a small part of metallic Ag gets oxidized for higher annealing time whereas no trace of oxidation of Au is observed. The surface morphology of the as-deposited and post-annealed alloy films are characterised by FESEM and AFM measurements. Due to thermal diffusion of Ag and Au, resultant narrow size distributions of the bimetallic Ag–Au nanoparticles are observed on the surface. The film morphologies suggest that the evolutions of bimetallic Ag–Au nanoparticles are nearly spherical in shape with an average aspect ratio value of ∼1.5.

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Surface morphology and wetting property of silver nanocluster-deposited films have been comprehensively investigated. A gas aggregation-type magnetron sputtering process is used to produce Ag nanoclusters, and the films are prepared by varying the cluster ion currents. The morphological result suggests that the deposited clusters agglomerate over the surface and also the overall size distribution is affected with increasing ion current. The morphological data are used to characterize various statistical parameters of the surface such as the interface width, autocorrelation function, power spectral density function, and fractal dimensions of the films. The X-ray photoelectron spectroscopy study reveals that the produced Ag nanostructures are made of pure metallic silver, and the total atomic concentration of silver on the surface increases with the increase of cluster ion currents. Wettability study of the films reveals that the morphological parameters along with the changing surface chemistry influenced the wetting property of the films. A sudden transition in surface wettability from hydrophilic to hydrophobic is observed for the films measured via water contact angle measurements. The comparison with the theoretical values suggests that the nanostructures produced for higher ion currents follow the Wenzel’s model. Finally, a correlation between the fractal dimension and the water contact angle values has been observed.