Synthesis and patterning of nanostructures of (almost) anything on anything
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چکیده
A necessary and very challenging condition for progress in nanoscience is being able to synthesize the requisite material. While there has been substantial success for some materials, one would like to develop protocols to fabricate structures of a wide variety of materials on an equally wide range of supports, preferably with size selection and the ability to pattern on large areas at low cost. The paper by Kerner and Asscher in this issue [1] is significant because it shows how at least some of those conditions can be satisfied in a novel and creative way. Building on the techniques of surface science, many researchers have focused on physical vapor deposition and the subsequent assembly of 1D wires, 2D islands, and 3D clusters. The problem, of course, is that Nature provides rather stringent rules that prevent the spontaneous assembly of 3D structures for all but a few materials. In particular, 3D growth will occur only if the adatoms interact only weakly with the surface but strongly with one another, with details dictated by surface and interface energies. A technique was developed a few years ago that by-passed these rules, termed buffer-layer-assistedgrowth (BLAG) [2–4], and the paper by Kerner and Asscher combines this technique with laser induced thermal desorption to form patterns in a novel and potentially important way. The idea behind buffer layer assisted growth is remarkably simple, as depicted in Fig. 1. The buffer layer replaces adatom–substrate interactions with very weak adatom–buffer interactions so that balling-up occurs out of contact with the substrate. The buffer must subsequently be removed so that the clusters are delivered in the ultimate of soft landings to the substrate where wetting is frustrated by kinetics. While there
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تاریخ انتشار 2004