The Physics & Astronomy Colloquium Series presents Gary Leach of Simon Fraser University, discussing "Single-Crystal Plasmonics  - Adventures in Hot Electron HarvestingI" on September 20.

Abstact: I describe efforts in our laboratory to address the challenges of plasmonic hot electron science through the fabrication and characterization of plasmonic photovoltaic structures, shortwave infrared optical sensors, and new catalyst materials for green energy applications. Our work highlights the integration of three pillars of device efficiency: (i) surface plasmon excitation, (ii) plasmon decay and hot carrier transport, and (iii) rectification of the carrier’s energy across an interface.

These concepts underly the design and fabrication of silver-zinc oxide Schottky junction, plasmonic photovoltaic devices, built and tested to establish structure-function relationships that underpin device performance. Our work demonstrates: (i) a novel deposition technique for the PVD evaporation of ultrasmooth, single-crystal silver thin films; (ii) a low-cost, single step, high fidelity nanopatterning technique; (iii) prism-coupled plasmonic photovoltaic devices that exhibit world-best performance by the internal photoemission mechanism (11.2% QE @ 543nm); and (iv) a low-cost, free-space coupled, nanostructured design, that exhibits strong second order nonlinear optical response and optical absorbance that informs the interpretation of the nanostructure’s photovoltaic response.

This work motivated the development of a new, scalable, epitaxial electroless deposition method to grow ultrasmooth, single-crystal noble metal films and nanostructures on silicon-supported silver substrates. These solution-deposited films are ideal for subtractive patterning of nanostructures through ion beam milling, and high definition, sub-wavelength single-crystal nanostructures through lithographic patterning methods. This approach provides a novel platform to deposit single-crystal metals for optical sensors and metal alloys for catalytic purposes.  Ultrasmooth, single-crystal alloy surfaces with tunable composition enable the identification of improved facet-specific catalyst compositions and improved electrocatalysts for the hydrogen evolution reaction and CO2 reduction reaction in alkaline media.  A new high surface area catalyst platform shows photo-electrocatalytic response mediated by surface plasmons i.e. hot electron-based plasmon-assisted electrocatalysis.