Stabilization of Plasmonic Silver Nanostructures with Ultrathin Oxide Coatings Formed Using Atomic Layer Deposition
Arin S. Preston, Robert A. Hughes, Nathaniel L. Dominique, Jon P. Camden, Svetlana Neretina
Abstract
Even though performance metrics position silver as the preeminent plasmonic material in the visible and near-infrared regions of the electromagnetic spectrum, it remains underutilized in applications because its properties irreversibly degrade in the environments it must operate. The emergence of shell-isolated plasmonic nanostructures as a distinct class of nanomaterials has, however, created new opportunities for the utilization of silver because its vulnerable surfaces can be encapsulated in a chemically robust transparent shell while maintaining important plasmonic properties. To fully capitalize on this opportunity requires that shell−nanostructure combinations be rationally designed where consideration is given to a parameter space encompassing nanostructure stability–property relationships. Herein, we demonstrate the layer-by-layer deposition capabilities of the atomic layer deposition (ALD) technique as a means to design shell-isolated silver nanostructures where the confined structure acts as a built-in plasmonic sensor for spectroscopically evaluating durability in air, water, and chemically aggressive environments. For all cases, appropriately designed oxide shells are shown to provide long-term stability, but where their own surface chemistry and structural integrity become limiting factors in bolstering and preserving plasmonic properties. The work, therefore, forwards the use of ALD-deposited layers for the realization of shell-isolated plasmonic nanostructures that exploit the remarkable properties of silver.