(274i) Optical Properties of Plasmonic Nanostructures with Interconnects and Sub-10 Nm Nanogaps

The optical properties of plasmonic nanostructures are critical to new applications in photocatalysis, photodetection, optical sensors, and solar energy conversion. Each of these applications is driven by excitation of plasmon resonances with intense electric fields that surround nanostructures illuminated by light. These localized electric fields are most intense in nanogaps between structures where electric field enhancements can be greater than 1000. The intense electric fields may generate hot carriers and photocurrents, or stimulate electronic transitions in adsorbates to drive chemical reactions. For these reasons, there is an ongoing effort to create reproducible nanogaps with interparticle distances as small as 1 nm. Most methods developed to date are difficult to scale and don’t provide a means for sub-nanometer precision. In this paper, we will describe optical properties of plasmonic nanostructures with sub-10 nm nanogaps fabricated by atomic layer deposition (ALD). We also investigate optical properties of nanostructures with electrical interconnects, which are necessary for optoelectronic device functions. Finite-difference time-domain (FDTD) simulations are used to analyze nanostructures to compare theory and experiment, and to better understand how structural features affect optical properties. We find that optical properties are highly sensitive to the shapes of nanostructures, and these shapes are strongly influenced by thermal effects during ALD processing. We will present experimental extinction data and FDTD simulations to analyze nanostructures made of different materials and compare experiment and theory. We will also discuss how optical properties of nanostructures are modified by adding electrical interconnects.