Electrochemical nanolithography

STM has tremendous potential in metal deposition studies. The initial stages of metal deposition and the Ag adlayer on Auflll] have been studied by Kolb et al. [91]. The inherent nature of the deposition process which is strongly influenced by the defect structure of the substrate, providing nucleation centers, requires imaging in real space for a detailed picture of the initial 

Application of an AFM tip as a nib to directly deliver organic molecules onto suitable substrate surfaces, such as Au, is referred to as dippen nanolithography [DPN] method [103-105]. When AFM is used in air to image a surface, the narrow gap between the tip and surface behaves as a tiny capillary that condenses water from the air. This tiny water meniscus is actually an 

The tiny water meniscus on the AFM tip was used as a nanosized electrochemical cell, in which metal salts can be dissolved. 

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Figure 10.9 Schematic diagram of electrochemical nanolithography. (Reprinted with permission from Langmuir, Direct Electrochemical Nanopatterning of Polycarbazole Monomer and Precursor Polymer Films Ambient Formation of Thermally Stable Conducting Nanopatterns by S. Jegadesan et al., 22, 2. Copyright (2006) American Chemical Society)...

The temperature dependence of the electrical resistance values of the polymer in the range of 30-125°C is such that it can be used as a thermal sensor." When solid carbazole crystals are immobilized on an electrode surface, oxidative dimerization and polymerization can also be achieved in solid state." By means of electrochemical nanolithography, conducting nanopatterns due to the selective oxidative crosslinking of PVK can be produced. 

O. de Abril, A. Gundel, R Maroun, R Allongue, R. Schuster, Single-step electrochemical nanolithography of metal thin films by localized etching with an ARM tip. Nanotechnology 19 (2008) 325301. 

Figure 1.3 Electrochemical nanolithography [89]. Reproduced by kind permission from the publisher.

Making templates of ordered nanopores is the starting point for template based nanolithography. The next step involves filling the pores of the membrane with different materials of interest using one or more available methods. The methods include electrochemical deposition (ED), vapor phase deposition such as chemical vapor deposition (CVD), pressure injection of molten metals and sol-gel methods. In this section we describe some of the methods of deposition in the nanopores. 

Dip-pen nanolithography is a high resolution patterning technique that enables the creation of patterns from the sub lOOnm to many micrometers length scale.76 This technique uses an ink-coated AFM (atomic force microscopy) tip as a nanopen. The ink molecules are transported from the tip to a substrate, normally by capillary forces when the tip is in contact with the surface of the substrate.77 The driving force for such transport is chemisorption of the ink to the underlying substrate due to a chemical78 or electrochemical force.79... 

Most of the time, metal/dielectric nanocomposites are studied in the form of solutions or thin solid films on a substrate Colloids, doped and annealed glasses, sol-gels, surfactant-stabilized nanoparticles, micelles, two- or three-dimension self-assembled nanocomposites, self-organized mesoporous oxides filled with metals, electrochemically-loaded template membranes, metal-ion implanted crystals, nanocomposite films elaborated by laser ablation, cluster-beam deposition, radio-frequency sputtering, or nanolithography. 

As seen in Figure 4.22, the immersion force can be significant between particles whose radii are larger than few nanometers. It has been found to promote the growth of 2D crystals from colloid particles [294-297], viruses, and globular proteins [298-304]. Such 2D crystals have found various applications in nanolithography [305], microcontact printing [306], as nanostructured materials in photo-electrochemical cells [307], in photocatalytic films [308], photo- and electroluminescent semiconductor materials [309], as samples for electron microscopy of proteins and viruses [310], as immunosensors [311], etc. (for reviews see Refs. [37,312]). 

The Electrochemical Dip-Pen Nanolithography (E-DPN) leads to direct writing of PTh nanowires (diameter less than 100 nm) on ihe surface of semiconducting or insulating materials, thus allowing the fabrication of complex structures which are proposed for the design of devices with multipurpose applications (electronics, defense, pharmaceutics, and biotechnology) [171]. 

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