Fabrication of Ag nanostructures by the systematic control of annealing temperature and duration on GaN (0001) via the solid state dewetting

Abstract

The gradual evolution of Ag nanostructures in terms of the configuration, size, and density of via the solid state dewetting is demonstrated on GaN (0001) by the systematic control of annealing temperature and duration with various Ag film thickness. Upon the annealing between 150 and 700 °C with the 20 nm Ag film, the hillocks, voids, irregular, and round dome shaped Ag nanoparticles (NPs) are fabricated based on various growth mechanisms: i.e., thermal diffusion and sublimation as well as the surface energy minimization. On the other hand, along with the systematic control of annealing duration between 0 and 3600 s with 10 nm Ag film 700 °C, the Ag NPs show gradually decreased size and density based on the concurrent influence of the Ostwald's ripening and sublimation of Ag atoms. The Raman, photoluminescence, and reflectance spectroscopy of the resulting Ag NPs are characterized in accordance with the various morphology evolution of Ag nanostructures.

Ag-AgO nanostructures on glass substrates by solid-state dewetting: From extended to localized surface plasmons

“…Annealing in air induces the formation of holes, their percolation, and appearance of elongated islands that finally achieve rounded shape, in agreement with the previous studies. [17][18][19][20][21][22]29 The process is completed at a temperature that depends on the initial film thickness: the thicker the initial film, the larger the annealing temperature required to complete the process. A representative scheme of the solidstate dewetting mechanism for a Ag film depending on the annealing temperature and the film thickness is presented in Figs.…”

“…It should be noted that at higher temperatures, the evolution of NPs can be affected, in addition to the surface diffusion, by the sublimation process that depends on the equilibrium vapor pressure increasing with the annealing and time temperature. 20 The final morphology of the nanostructures at the different stages of the process depends on the initial film thickness and the annealing conditions such as annealing time and temperature.…”

“…15,16 During the transformation, a series of modifications in metal films are induced: formation of hillocks or strain-free extrusions, growth of holes within the film, and agglomeration of islands leading to a discrete structure. [17][18][19][20][21][22] This manufacturing process allows covering the whole path between a continuous film and three-dimensional nanostructures, and therefore, tuning the morphology and the optical features such as surface plasmons (SPs) to optimize a particular property. The fabrication of Ag nanostructures by thermal annealing of thin films has been reported in diverse works controlling parameters such as the annealing temperature, the annealing time, and the deposition amount, evaluating even the final SERS response.…”

“…The fabrication of Ag nanostructures by thermal annealing of thin films has been reported in diverse works controlling parameters such as the annealing temperature, the annealing time, and the deposition amount, evaluating even the final SERS response. 19,20,23,24 In a previous work, we analyzed the morphological and optical transitions from continuous films to discrete nanostructures for the case of Au films treated thermally at different temperatures. 21 Here, we extend the study to Ag with the highest extinction cross section coefficient associated with the excitation of SPs and showing SERS enhancement factors of 10 5 .…”

Compositional effect on the fabrication of AgxPd1−x alloy nanoparticles on c-plane sapphire at distinctive stages of the solid-state-dewetting of bimetallic thin films

“…41 As the increase of P T is exponential with the T a , the R e can be signicantly increased with T a . As evidenced by the EDS spectra in Fig.…”