Solution chemistry approach to fabricate vertically aligned carbon nanotubes on gold wires: towards vertically integrated electronics

Abstract

A monolayer of hexadecyltrichlorosilane, 3-aminopropyltriethoxysilane or 3-mercaptopropyltrimethoxysilane was self-assembled onto a p-type silicon (100) substrate to provide a resist for electrochemical anodization with an atomic force microscope cantilever. Silane treatment of the oxide nanostructures created by anodization lithography allowed for the creation of a chemically heterogeneous surface, containing regions of −NH 2 or −SH surrounded by −CH 3 functionality. These patterned regions of −NH 2 or −SH provided the point of attachment for citrate-stabilized gold colloid nanoparticles, which act as 'seed' particles for the electro-less deposition of gold. This has allowed the creation of gold wires on a silicon surface. Carbon nanotubes, with high carboxylic acid functionality, were vertically immobilized on the patterned gold wires with the use of a cysteamine monolayer and a condensation reaction. Such a material may prove useful in the creation of future vertically integrated electronic devices where it is desirable for electron transport to be in three dimensions and this electron transport is demonstrated with cyclic voltammetry.

Patterned Transparent Conductive Au Films through Direct Reduction of Gold Thiocyanate

“…[ 4 ] Bottom-up techniques generally rely upon molecular self-assembly phenomena to produce defi ned structures that could be practically utilized. Patterned gold fi lms can be assembled with the use of NPs organized on surfaces through chemical derivation of the particle surface [ 7 ] and/or the substrate supporting the fi lm growth, [8][9][10] or through the aid of physical templates. The propensity of Au ions to self-assemble and undergo reduction into colloids and NPs, however, poses distinct barriers for utilizing conventional gold chemistry for creating structurally defi ned, organized thin fi lms.…”

“…The propensity of Au ions to self-assemble and undergo reduction into colloids and NPs, however, poses distinct barriers for utilizing conventional gold chemistry for creating structurally defi ned, organized thin fi lms. Patterned gold fi lms can be assembled with the use of NPs organized on surfaces through chemical derivation of the particle surface [ 7 ] and/or the substrate supporting the fi lm growth, [8][9][10] or through the aid of physical templates. [ 5 , 11-14 ] These approaches exhibit shortcomings, both conceptually as well as technically.…”

Length‐Selective Chemical Assembly of Vertically Aligned Carbon Nanotubes

“…The chemical assembly route taken to vertically align CNTs is more cost‐effective and allows for greater flexibility in selecting the CNT–substrate interactions and the substrate used. In this regard, vertical self‐assembly of CNTs have been achieved on different substrates, including ITO, gold, silver, silicon, glass and Nafion films, through metal‐assisted chelation, electrostatic interactions, π–π interactions, and different covalent bonds …”

Solution-Based Photo-Patterned Gold Film Formation on Silicon Nitride

“…Surface capture of nanoparticles-by specific and nonspecific attachment mechanisms-is a possible solution-based route to surface metallization. [9][10][11][12] Electroless plating is a compelling alternative: a solution-based process useful for metallizing a wide variety of materials, including nonconductive and irregularlyshaped materials. 7,[13][14] Solution access, rather than line-of-sight as in physical vapor deposition, dictates where surface plating will occur, so that electroless plating is an appealing choice for fashioning nanofluidic devices where even irregular and concealed surfaces may require metallization.…”