Arrays of metallic micro-/nano-structures by means of colloidal lithography and laser dewetting
Résumé
Long-range arrays of prismatoid metal nanostructures are fabricated by a hybrid methodology, i.e. using Langmuir microsphere films and laser-assisted dewetting. As the initial step, we use colloidal lithography. Monolayers of 1-5 mu m polystyrene microspheres covered with a thermally evaporated Ag or Au thin film of controlled thickness (5-50 nm) are then used as masks to pattern the surface of quartz, BK7 glass or silicon substrates, typically in the order of cm(2). When removing the spheres by physico-chemical means (ultrasound bath and solvent wash), the resulting surface shows an array of nm-size prismatoid structures (Fischer patterns), that can be further processed by laser. Thus, by using two different lasers (355-nm wavelength, 50-ps duration and 193-nm wavelength, 15-ns duration) for the metal dewetting, we control the shape of the deposited nanostructures. A detailed study is presented here on the reshaping of such metal structures through laser annealing. This new hybrid methodology expands the panel of microsphere-assisted technologies employed in preparing surface nanomaterials. (C) 2015 Elsevier B.V. All rights reserved.