title: Fabrication of suspended metal-dielectric-metal plasmonic nanostructures.
abstract: Dipole nano-antennas have predominantly been investigated in their lateral orientation with their long axes in plane with a supporting substrate. However, the response of coupled dipole antennas oriented vertically to a supporting substrate has so far been out of experimental reach. Here, we present a self-aligned electron-beam lithography technique for fabricating such antennas consisting of metal nanostructures on both sides of a suspended silicon nitride membrane. This 30 nm thick membrane provides an ultra-smooth metal/dielectric interface and uniformly defines the antenna feed-gap size in an array of antennas. It is also a suitable substrate for probing the nano-antenna response with monochromated electron energy-loss spectroscopy (EELS) in a transmission electron microscope. We provide details of this double-sided patterning process, and show the excitation of hybridized plasmon modes in EELS with electrons directed along, and at an angle to, the antenna axis.
authors.affiliation: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, 117602, Singapore.
authors.forename: Zhaogang
authors.initials: Z
authors.lastname: Dong
authors.forename: Michel
authors.initials: M
authors.lastname: Bosman
authors.forename: Di
authors.initials: D
authors.lastname: Zhu
authors.forename: Xiao Ming
authors.initials: XM
authors.lastname: Goh
authors.forename: Joel K W
authors.initials: JK
authors.lastname: Yang