Epitaxially aligned single-crystal gold nanoplates formed in large-area arrays at high yield

Well-tailored nanomaterials with a single-crystal character provide ideal building blocks for on-chip plasmonic devices.Although colloidal methods have demonstrated mastery over the synthesis of such structures,it has proven quite difficult to deploy these same nanomaterials on substrate surfaces in a highly deterministic manner where precise control over position and orientation is ensured.Herein,we demonstrate a room-temperature two-reagent liquid-phase seed-mediated synthesis of gold nanoplates directly on substrate surfaces in arrays over a square-centimeter area.The synthesis is reliant on benchtop lithographic and directed-assembly processes that give rise to single-crystal seeds of gold that express both an epitaxial relationship with the underlying substrate and the internal defect structure required to promote a two-dimensional growth mode.The resulting structures are highly faceted and,because seed-substrate epitaxy is imposed upon the growing nanoplates,are identically aligned on the substrate surface.Nanoplate yields are increased to values as high as 95%using a post-processing sonication procedure that selectively removes a small population of irregularly shaped nanostructures from the substrate surface,and in doing so,gives rise to an uncompromised plasmonic response.The work,therefore,advances the techniques needed to integrate single-crystal nanomaterials with wafer-based technologies and provides leading-edge capabilities in terms of defining large-area arrays of plasmonic structures with the nanoplate geometry.