Self-organized patterned arrays of Au and Ag nanoparticles by thickness-dependent dewetting of template-confined films (original) (raw)
Related papers
Template-confined dewetting of Au and Ag nanoscale films on mica substrate
Applied Surface Science, 2013
In this work we report about the template-confined dewetting of Au and Ag nanoscale films on mica substrate toward surface patterning control. In this approach, the Au and Ag surface pattern order, on the mica substrate, is established by the template confined deposition on a micrometric scale, while the dewetting process is induced by thermal process. We expose the results of our studies on the dewetting kinetics both for Au and Ag on mica consisting, in particular, in the identification of three regimes of the process: a regime I in which holes nucleation in the Au and Ag films occurs (characterized by 130 and 72 meV activation energies, respectively); a regime II consisting in the retraction phenomenon of the films limited by the Au or Ag surface diffusion; a regime III corresponding to the merging of the dewetted fronts of holes that come close to each other (and formation of Au and Ag nanoparticles as a consequence). Correspondently, the ordered surface patterns realized for the Au and Ag arrays of nanostructures on a large scale (micrometric) can be changed and controlled for specific applications.
We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900°C). From these analyses, quantitative evaluations on the NPs size evolution are drawn.
Periodical distribution of Au nanoparticles through dewetting on patterned substrates
Applied Physics Letters, 2020
Metal nanoparticles (NPs) are widely applied in many fields, such as optics, electronics, and sensor platforms. The size and density of the NPs play important roles in device performance and nanostructure distribution. In this paper, the periodically distributed Au NPs are obtained by dewetting the Au film or Au-Ge film on a patterned SiO 2 substrate. The influence of the substrate morphology and the Ge film on the dewetting process is investigated. The former modifies the crucial dewetting parameters periodically, i.e., the surface curvature, while the latter provides energy for Au atoms' surface diffusion. The extinction spectrum shows a prominent enhancement in local surface plasmon resonance, over 5 times in the visible region, which is due to the periodicity and high-density in NP distribution. This study provides a simple and regulable method to prepare periodically distributed metal NPs.
Dewetting of Au nanoparticle assemblies
Journal of Materials Chemistry, 2011
Atomic force microscopy measurements as a function of annealing temperature, time of exposure to a high relative humidity environment, and scan duration/parameters have been used to ascertain the stability of assemblies of thiol-passivated Au nanoparticles on silicon substrates. Striking changes in the morphology of self-organised nanoparticle patterns are observed following the exposure of samples to atmospheres with a relative humidity of 80%. The nanoparticle film dewets the underlying silicon substrate on exposure to water, forming locally thicker regions. Time-lapse imaging shows that the dewetting proceeds via layer-by-layer growth, and there is no evidence for classical coarsening mechanisms involving self-similar film morphologies. Annealing at temperatures between 100 C and 160 C produces a rather different dewetting effect for the highest temperatures and/or annealing times, where significant nanoparticle sintering promotes the break-up of the two-dimensional assembly. The morphology of the initial 2D film plays a key role in determining the time scale on which annealing promotes nanoparticle dewetting. Dewetting can also be induced by a scanning probe such that localised (micron-scale) areas of the nanoparticle assembly can be converted from 2D to 3D character.
Vacuum, 2014
In this work we report about the template-confined dewetting of Au nanoscale film on SiC substrate in view of a surface patterning control. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition on a micrometric scale. Then, a film dewetting process is induced by thermal processes. Using scanning electron microscopy analyses, we studied the dewetting kinetics for Au on SiC and we identified three regimes of the process: a regime I in which holes nucleation in the Au film occurs (characterized by 248 meV activation energy); a regime II consisting in the retraction phenomenon of the film limited by the Au surface diffusion; a regime III corresponding to the merging of the dewetted fronts of holes that come close to each other (resulting in formation of Au nanoparticles). Correspondently, the ordered surface patterns obtained for the Au arrays of nanostructures on a large scale (micrometric) can be changed and controlled for specific applications.
Effect of surface type on structural and optical properties of Ag nanoparticles formed by dewetting
Optics Express, 2013
Integration of an array of Ag nanoparticles in solar cells is expected to increase light trapping through field enhancement and plasmonic scattering. Requirement of Ag nanoparticle decoration of cell surfaces or interfaces at the macro-scale, calls for a self-organized fabrication method such as thermal dewetting. Optical properties of a 2D array of Ag nanoparticles are known to be very sensitive to their shape and size. We show that these parameters depend on the type of the substrate used. We observe that the average nanoparticle size decreases with increasing substrate thermal conductivity and nanoparticle size distribution broadens with increasing surface roughness.
Thickness-dependent spontaneous dewetting morphology of ultrathin Ag films
Nanotechnology, 2010
We show here that the morphological pathway of spontaneous dewetting of ultrathin Ag films on SiO 2 under nanosecond laser melting is found to be film thickness dependent. For films with thickness h between 2 ≤ h ≤ 9.5 nm, the morphology during the intermediate stages of dewetting consisted of bicontinuous structures. For films 11.5 ≤ h ≤ 20 nm, the intermediate stages consisted of regularly-sized holes. Measurement of the characteristic length scales for different stages of dewetting as a function of film thickness showed a systematic increase, which is consistent with the spinodal dewetting instability over the entire thickness range investigated. This change in morphology with thickness is consistent with observations made previously for polymer films [A. 1 energy curvature that incorporates intermolecular forces, we have estimated the morphological transition thickness for the intermolecular forces for Ag on SiO 2 . The theory predictions agree well with observations for Ag. These results show that it is possible to form a variety of complex Ag nanomorphologies in a consistent manner, which could be useful in optical applications of Ag surfaces, such as in surface enhanced Raman sensing.
Journal of Materials Science: Materials in Electronics, 2014
Patterned metallic thin films have attracted a lot of attention, in recent years, due to their wide technological applications. On the basis of this fact, in the present work, we illustrate a simple, versatile, and low-cost methodology to prepare surface micro-patterns in nanoscale deposited Au films. The methodology is based on the following steps: (a) to perform nanoscale Au film depositions assisted by micrometric templates to obtain the deposited Au film micrometric patterned in specific and desired ways (micrometric squares, hexagons, …), and (b) by low-temperature thermal processes (\300°C) to induce a dewetting process of the PMMA to guide specific patterning effects in the top nanoscale Au film. In this approach, the Au surface pattern order is established by the template confined deposition on a micrometric scale while the realization and control of the Au surface pattern is given by the control of the dewetting process of the underlaying substrate, without invoking high temperature thermal processes.
Journal of Magnetism and Magnetic Materials, 2019
In this paper, we introduce a method for the assembly of micropatterned bimetallic nanoparticles (NPs) withcontrollable patterns and particle sizes on laser interferencestructured substrates. The microstructures of interference patterning in conjunction with the nanostructures fabricated by the direct laser interference ablation (DLIA) were used as the templates for the assembly of patterned NPs in thermal dewetting processes. The location and particle size of micropatterned Au-Ni NPs formed were well-controlled by the nanostructures on the substrate surface. The magnetic domain pattern of as-annealed Au-Ni NPs is consistent with the topography of the silicon templates. The DLIA method provides a one-step new way for the large-area and high throughput fabrication of patterned NPs with the templated dewetting method. It can be easily extended to many metal combinations and has wide applications such as magnetic recording, plasmon-enhancement and other functional nanostructured elements and devices