# Self-Organized Conductive Gratings of Au Nanostripe Dimers Enable Tunable Plasmonic Activity
## 2 Results and Discussion
### Plasmonic and Conductive Nanostripe Arrays
In panel (**a**) the nanostripes’ aspect ratio _l/w_ was increased from 0.21 (blue spectra) to 0.28 (red spectra), by increasing the height \(h\) from 22 nm to 30 nm; in panel (**b**), _l/w_ was increased from the green to the black curve by decreasing the width of the nanoantennas; (**c**) sketch of the circuit exploited for measuring the sheet resistance (\(R_{s}\)) parallel to the main axis of the nanostripes (size of the circuit: 2 \(\times\) 2 mm\({}^{2}\)); (**d**) plot of \(R_{s}\) measured in-situ during the growth of Au nanoantennas at \(\theta_{2}\) = 50\({}^{\circ}\) (green curve), 60\({}^{\circ}\) (blue curve) and 70\({}^{\circ}\) (red curve) respectively; and (**e**) SEM image of Au nanostripe arrays confined on the narrow facets under glancing condition (\(\theta_{2}\) = 80\({}^{\circ}\)): a strong shadowing effect is observed at the inter-ripple connection (red circles) with no gold or disconnected nanoclusters. These regions limit the electrical conductivity at the early stages of the Au evaporation process. The scale bar corresponds to 1 \(\upmu\)m.  
narrow, steep ridges (as sketched in Figure 1e) at the incidence angle \(\theta_{2}\) of 50\({}^{\circ}\) (green dots), 60\({}^{\circ}\) (blue dots) and 70\({}^{\circ}\) (red dots), respectively. The plots show \(R_{\rm s}\) as a function of the Au thickness, \(d\), deposited on the glass facets, and reveal that electrical percolation takes place for all three depositions. The onset of the electrical continuity occurs at 23 nm, 56 nm and 66 nm for growth performed at 50\({}^{\circ}\), 60\({}^{\circ}\) and 70\({}^{\circ}\), respectively. At the early stages of the process, geometrical shadowing at the inter-ripples defects, more pronounced under grazing growth, limits the electrical connection between consecutive nanostripes. This effect is well demonstrated by the SEM image of Figure 2e, corresponding to thin Au nanostripes grown under grazing incidence evaporation (\(\theta_{2}\) = 80\({}^{\circ}\)). Local interruption of the nanostripes is observed in correspondence with the confinement of locally disconnected Au nanoclusters, due to the pronounced shadowing effect from the defect regions at the ripple ends (see red circles in Figure 2e). The macroscopic electrical transport observed in the sheet resistance measurements (Figure 2d) corresponds to the condition of local percolation between micrometric nanostripes at the inter-ripples' defect regions. Under this condition, a drop of the sheet resistance is observed, followed by a power law decrease, which is as expected for percolative systems [33; 34]. Remarkably, very low sheet resistance values, in the range of few Ohm/sq, were measured for all three samples. Under these conditions, the nanoelectrodes behave as wire grid polarizers [35] in the near-IR spectrum, with the transversal transmittance exceeding 80%, while the longitudinal one is attenuated below 10%, at a wavelength of above 950 nm. The good electrical transport of the self-organized nanostripe antennas [36] represents a relevant property of these large-area metamaterials in view of the implementation of plasmonic nanodevices for biosensing, nano-optics and/or photon-harvesting applications.