Directed self-assembly of nanorod networks: bringing the top down to the bottom up

Abstract

Abstract. Self-assembled electrodeposited nanorod materials have been shown to o↵er an exciting landscape for a wide array of research ranging from nanophotonics through to biosening and magnetics. However, until now, the scope for site-specific preparation of the nanorods on wafers is limited to local area definition. Further there is little or no lateral control of nanorod height. In this work we present a scalable method for controlling the growth of the nanorods in the vertical direction as well as their lateral position. A focused ion beam (FIB) pre-patterns the Au cathode layer prior to the creation of the Anodized Aluminium Oxide (AAO) template on top. When the pre-patterning is of the same dimension to the pore spacing of the AAO template, lines of single nanorods are successfully grown. Further, for sub-200 nm wide features a relationship between the nanorod height and distance from non-patterned cathode can be seen to follow a quadratic growth rate obeying Faradays law of electrodeposition. This facilitates lateral control of nanorod height combined with localised growth of the nanorods.

Utilizing Dog-Boning to Build up High-Aspect-Ratio Nanofences

“…where Z is the ionic number and F the Faraday constant. 21 Hence, if the electrode area stays constant during deposition, the height h of the resulting layer is then proportional to n and can be expressed via…”

“…12,13 Most applications require structures covering macroscopic areas, such as: arrays of ultramicroelectrodes, 14 advanced catalysts 15 and optical experiments on plasmonic nanowire arrays 16 for potential use in biosensing. 17 Hence, pre-structuring the working electrode has only been investigated at smallest possible electrode layer thicknesses [18][19][20][21] to keep the used gold amount at a minimum. Attempts to restrict the lateral confinement of the array by covering the porous template prior to deposition [22][23][24] or by subsequent laser removal of parts of the array 25 led to fringed rims, unsuitable for more sophisticated integrated designs.…”