(Color online) (a) Process flow for fabricating metal (Au) nanostructures on a SiN membrane. (b) Scanning electron micrograph (SEM) of 10 nm holes patterned in PMMA, angle-deposited with 2 nm of Ti prior to imaging. (c) SEM of sub-10 nm Au dots on the SiN membrane after lift-off.
SEM images of Au nanostructures (a) before and (b) after annealing in an RTP at under flow. The annealing step reshaped the nanostructures to form regularly shaped rounded structures.
[(a) and (b)] SEM images of an array of Au nanostructures with (a) elongated and (b) rounded geometries with a range of different sizes. [(c) and (d)] Bright-field TEM images of the corresponding shapes showing the polycrystallinity of the lithographically defined Au structures.
SEM images of Au nanostructures patterned in [(a), (b), and (d)] a trimer configuration and [(c) and (e)] dimers with triangle and ring geometries.
(Color online) (a) STEM image of a teardrop-shaped nanostructure. The EELS data of the nanostructure are acquired in the form of a SI and are represented in (b)(i), where each pixel in the SI corresponds to an EEL spectrum. (b)(ii) Distribution of surface plasmons (pixels with bright intensity) around the nanostructure. The outline of the nanostructure is shown by the dashed line. (c) EEL spectra measured at the corresponding points on the nanostructure, as shown in (b)(i).
(Color online) (a) STEM image of an elongated nanostructure with sub-10 nm width. The EELS data of the nanostructure are acquired in the form of a SI and are represented in (b)(i), where each pixel in the SI corresponds to an EEL spectrum. [(b)(ii) and (b)(iii)] Distribution of longitudinal and transverse surface plasmon modes (pixels with bright intensity) around the nanostructure. Note that the longitudinal mode corresponds to hotspots at the left and right edges, while the transverse mode corresponds to hotspots on the top and bottom edges. The arrows indicate the direction of charge oscillations for the two modes. (c) Representative EEL spectra extracted at various regions of the nanostructure. The longitudinal, transverse, and bulk plasmon peaks are as indicated.
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