Nanostructured surfaces: challenges and frontiers in nanotechnology

Abstract

Nanostructured surfaces can be broadly defined as substrates in which the typicalfeatures have dimensions in the range 1–100 nm (although the upper limit of 100 nmmay be relaxed to greater sizes in some cases, depending on the material andthe specific property being investigated). The recent surge of interest in thesesystems stems from the remarkable effects that may arise from the critical sizereduction. Interesting novel properties (catalytic, magnetic, ferroelectric, mechanical,optical and electronic) occur as we reduce the dimensions from a practically infinite(and periodic) solid crystal to a system composed of a relatively small number ofatoms. So far, nanostructured materials or nanomaterials are perhaps the onlysub-field of nanoscience that has made the transition from fundamental science toreal world applications, thus becoming a technology (a good example of this arenanostructured surface coatings). This paper describes some selected examples of recentprogress in the study of nanostructured surfaces. Surface reconstructions, whichoccur either naturally or as a consequence of the interaction with adsorbates, arediscussed because of their importance in model chemical reactions and for theirpotential use as templates for the ordered growth of nanostructures. Supramolecularassemblies and molecular nanostructures, resulting from the balance betweenmolecule–molecule and molecule–surface interactions, are described because of theirfundamental interest and their potential use in nanoelectronic devices. Recentprogress in the growth of semiconductor nanostructures, in particular Ge–Si andInAs–GaAs, is briefly reviewed. A few selected examples of nanostructured functionalmaterials, such as ferroelectric and magnetic nanostructures, are discussed in view oftheir potential for applications in future data storage devices. Nanostructuredmaterials used in catalysis and gas sensor applications are briefly described. Finally,perspectives and future challenges in this emerging field of research are also discussed.