Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry

Abstract

Deep subwavelength integration of high-definition plasmonic nanostructures is of key importance in the development of future optical nanocircuitry for high-speed communication, quantum computation and lab-on-a-chip applications. To date, the experimental realization of proposed extended plasmonic networks consisting of multiple functional elements remains challenging, mainly because of the multi-crystallinity of commonly used thermally evaporated gold layers. This can produce structural imperfections in individual circuit elements that drastically reduce the yield of functional integrated nanocircuits. In this paper we demonstrate the use of large (>100 μm(2)) but thin (<80 nm) chemically grown single-crystalline gold flakes that, after immobilization, serve as an ideal basis for focused ion beam milling and other top-down nanofabrication techniques on any desired substrate. Using this methodology we obtain high-definition ultrasmooth gold nanostructures with superior optical properties and reproducible nano-sized features over micrometre-length scales. Our approach provides a possible solution to overcome the current fabrication bottleneck and realize high-definition plasmonic nanocircuitry.

Laser intensity effects in carrier-envelope phase-tagged time of flight-photoemission electron microscopy

“…Irregularities, such as bigger crystal grains or possibly unknown particles on the multicrystalline gold film surface, can be observed, whereas very smooth surfaces are visible on the ITO-coated glass and single-crystalline gold flake. It is well known that evaporated multicrystalline gold films exhibit a typical diameter of crystal grains of 30-50 nm [49]. Atomic force microscope (AFM) imaging on the investigated gold film confirms a crystal grain size of 30-50 nm in our case.…”

Influence of surface roughness on the optical properties of plasmonic nanoparticles

“…Recent publications report on the control of nanoscale roughness and its strong effect on the nanoparticles farand near-field optical properties. 9,10,12 However, varying surface roughness is often accompanied by varying crystallinity, and therefore the results do not allow for a clear distinction between the contributions of the surface and the bulk.…”

Three-dimensional concentration of light in deeply sub-wavelength, laterally tapered gap-plasmon nanocavities

“…These small features are difficult to achieve with nanosphere lithography; however, they could be potentially realized using planar fabrication techniques such as e-beam lithography 25 or ion tailored mask lithography 26 eventually combined with the use of a mono-crystalline gold film. 27 For a value of W neck ¼ 5 nm, whose fabrication feasibility has already been demonstrated, 26 we obtain V eff % 3 Â 10 À4 k 3 . For the more experimentally challenging case of W neck ¼ 2 nm, 25 we obtain V eff % 10 À5 k 3 .…”