Fabrication of Metal Nanowires Using Microcontact Printing

Abstract

Microcontact printing (µCP) is a versatile soft-lithographic technique to pattern substrates using an elastomeric stamp. We demonstrate the high-resolution capabilities of this technique for the fabrication of metal nanowires using either subtractive or additive patterning strategies. The subtractive method relies on printing a self-assembled monolayer (SAM) to protect a metal substrate selectively in a wetchemical etch process. We applied this approach to pattern Au, Ag, Cu, and Pd using eicosanethiol (ECT), and Al by printing hexadecanephosphonic acid (HDPA) as the resist-forming compound. As the etch process has to be selective and reliable, optimization of the etch chemistries is essential to obtain nanowires with excellent lithographic definition. The additive method involves the formation of wire template structures that can direct the electroless deposition (ELD) of a metal on a substrate. One variation of this approach entailed the patterning of a thin Au layer that was printed and etched to initiate ELD of Ag, Cu, and NiWP. Printing a colloidal Pd/Sn catalyst directly onto a substrate constitutes another variation of this patterning strategy. The use of a defined colloidal suspension as the ink, the derivatization of the stamp with poly-(ethylene glycol) (PEG), and the pretreatment of the substrate with an amino-functionalized silane were the key elements of this approach, which was demonstrated for the fabrication of NiB and CoP nanowires. Devices with arrays consisting of 400-µm-long wires with 1 µm pitch were produced with these patterning strategies, and wire dimensions of 150-500 nm in width were achieved depending on the fabrication parameters. We have characterized the resulting nanowires using atomic force microscopy (AFM), determined their morphological properties, and addressed their electrical performance.

Selective Assembly of Sub‐Micrometer Polymer Particles

“…Molding of PDMS was carried out as previously detailed. [ 15 ] Cured PDMS templates were immersed in ethanol for at least one day to extract low-molecular-weight silicone oils. Finally, templates were dried at 20 mbar for 1 h directly prior to use in assembly experiments.…”

Cold welding of organic light emitting diode: Interfacial and contact models

“…9 In most cases, the contact occurs around dust particles that are present in the clean room environment 10 These include materials such as silicone, silicon, silica and organic materials. The contacts are enhanced by the application of pressure, 3,[11][12][13][14][15] which is often applied through compliant materials such as poly-di-methyl-siloxane (PDMS). Such compliant layers improve the contacts between the cold welded layers.…”

Oxygen Attachment on Alkanethiolate SAMs Induced by Low-Energy Electron Irradiation

“…[1][2][3] The properties of SAMs (i.e., low thickness, densely packed, ordered stacking, high stability, choice of functional heading groups, and resistance against chemicals) 2,4 make these surface coatings suitable for varied applications including control of wetting and adhesion, 5,6 biosensors, 7 microcontact printing, 8 and cell adhesion. 2 Furthermore, these molecular assemblies present interesting structural and physicochemical properties (i.e., small thickness of about 1-3 nm and the molecular size of its structural elements) for radiation-induced nanostructure patterning lithography.…”