Shape‐Controlled 3D Periodic Metal Nanostructures Fabricated via Nanowelding

Abstract

A novel method for fabricating 3D metallic nanostructures to be used in polarized color filters based on nanoimprint lithography, electron-beam evaporation, and nanowelding is proposed. The shape of the nanostructures can be controlled by adjusting the temperature for the nanowelding process. Ag nanowires deposited on polymer patterns are accumulated by the nanowelding process to build up diverse 3D nanostructures. The morphologies of the fabricated 3D nanostructures are analyzed using scanning electron microscopy, atomic force microscopy, and focused ion beam; the heating temperature is varied from 90 to 130 °C in steps of 10 °C. In order to analyze the recrystallization phenomenon after welding, transmission electron microscopy is utilized. The 3D metallic nanostructure has different morphologies and optical properties corresponding to welding temperature conditions and accumulated layer thicknesses. Based on preliminary experimental results, the process parameters are optimized and a polarized color filter is fabricated. Optical characteristics of the filter are evaluated using polarizer and spectrometer. Through this work, it is shown that the proposed method is an effective way to realize various 3D metallic nanostructures for special optical properties, therefore the method based on nanowelding can be utilized in fabrication of functional metamaterials, optical filters, biosensors, and others.

Adhesive-Layer-Free and Double-Faced Nanotransfer Lithography for a Flexible Large-Area MetaSurface Hologram

“…Advantageously, the proposed method allows transfer to be conducted at low temperature that is independent of the employed material. In our previous works, we found that Au, Al, and Ag nanostructures can be melted and oxidized below 150 °C, , which highlights the importance of performing transfer at low temperature. Consequently, we selected PMMA as a flexible substrate with a low T g and used DSC analysis to show that the T g of the PMMA film with the thickness of 150 μm (Figure a).…”

Large-Area Nanogap-Controlled 3D Nanoarchitectures Fabricated via Layer-by-Layer Nanoimprint

“…The junction of the second and third Au layer can be observed in the HRTEM images (see Figure S4b-(3 and 4)). In previous studies, 3D metal nanostructures were developed via nanowelding technology. , However, the polymer mold had to be fabricated on PET or PMMA substrates using nanoimprinting resin. Therefore, defects could appear in the 3D metal nanostructures while fabricating the multilayer nanostructures due to repeated heating, and the bottom metal layer could be damaged.…”

Biocompatible Nanotransfer Printing Based on Water Bridge Formation in Hyaluronic Acid and Its Application to Smart Contact Lenses

“…Nanowelding, caused by nanoscale melting-point depression, allows stacking at low temperatures in the range of 90−120 °C. 24 Figure 2h shows an SEM image of a sample transferred onto a 2″ diameter HA film. Additional SEM images obtained at five different points on the patterned HA film reveal the uniformity of the entire area (Figure S6).…”