Degradation analysis and characterization of multifilamentary conduction patterns in high-field stressed atomiclayer-deposited TiO2/Al2O3 nanolaminates on GaAs J. Appl. Phys. 112, 064113 (2012) Following Ostwald ripening in nanoalloys by high-resolution imaging with single-atom chemical sensitivity Appl. Phys. Lett. 101, 121920 (2012) Novel doping for synthesis monodispersed TiO2 grains filled into spindle-like hematite bi-component nanoparticles by ion implantation AIP Advances 2, 032179 (2012) Effect of tungsten metal particle sizes on the solubility of molten alloy melt: Experimental observation of Gibbs-Thomson effect in nanocomposites

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Nanoscale self-assembly is a concept that Nature has been making use of since the beginning of life, [1] and we have only recently started realizing its potential for achieving better control over materials properties. An overwhelming number of self-assembly fabrication methods for the formation of nanocluster arrangements on surfaces have been found, and they feature processes having various timescales, complexities, and versatilities. The fabrication of such structures can be discussed in terms of two processing steps that are independent of the actual process sequence. First, nanocomponents must be formed, which can be accomplished in various ways from precursors in the liquid, solid, or gas phases employing either chemical or physical deposition processes. In the second step, the challenge is to organize the segregated and deposited nanoparticles into structures or patterns on surfaces. Several approaches that use either a serial-writing-type process [2] or templates that allow fast parallel processing [3,4] have been formulated. More simple are the template-free approaches based on self-organization, which is the autonomous organization of components into patterns without human intervention.[5]Among all of these approaches, wet-chemical strategies utilizing fluid mechanics appear to be the simplest and most effective. Evaporation of drops on nonfunctionalized substrates has been used for the patterned deposition of solutes in DNA microarrays.[6] Furthermore, the ring deposition of particles from colloidal dispersions deposited as droplets has also been shown. [7] In addition to droplet drying, combined flow drying has been utilized for the deposition of semiconductor nanowires and nanotubes onto functionalized substrates.[8] The self-organization of matter into regular sub-micrometer-and nanoscale lines by using the wetting instability of a Langmuir-Blodgett film [9,10] as a cost-effective method has also been discussed. However, structuring of nanocluster arrays or wirelike morphologies from a droplet still faces certain challenges. Yawahare et al. [11] have demonstrated the room-temperature formation of lines from a drop if three prerequisites are met: evaporation between partially wetted surfaces, the presence of a pinning point, and the availability of a surfactant. In contrast to the above approaches, this paper presents a droplet-deposition-based, template-free, and rapid (only a few seconds) approach for fabricating nanostructures without the use of any surfactant. Our general setup can be understood as the so-called "anti-Lotus effect". The Lotus effect [12] is well known for its removal of dust particles from the surface of a lotus leaf by gathering them into a droplet that is moving over the surface, thus cleaning it. The effect is based on the ability of certain surfaces to form spherical droplets with contact angles near 180°(i.e., superhydrophobic), enabling the incorporation of surface particles as well as a reduction in friction. In contrast to this, our work makes use of an anti-Lotus effect,...

The usability of nanostructures in electrical devices such as gas sensors critically depends on the ability to form high quality contacts and junctions, at least in a two terminal setup. For the fabrication of various nanostructures, vapor-liquid-solid (VLS) growth is meanwhile a widely spread and very efficient technique for many semiconductors. However, as already demonstrated in the literature, forming contacts with the VLS grown structures to utilize them in a device is typically tedious. Either the substrate material has to be the same, such as the VLS material, or a laborious procedure has to be used to connect one side with the other. As a strikingly simple alternative approach, we report that the ability of VLS grown nanostructures to interpenetrate each other in a homoepitactical manner can be used to form a connecting bridge between two gold contact lines on a microchip. Other methods of direct growth are already established, but they lead only to a touching of the nanowires and not to interpenetration. The ZnO interpenetration junctions can be directly used as electrical devices, and just as a proof of principle, they were employed as UV-light dependent resistor, field effect transistor (FET), or gas sensor.

One-step device fabrication through the integration of nanowires (NWs) into silicon microchips is still under intensive scientific study as it has proved difficult to obtain a reliable and controllable fabrication technique. So far, the techniques are either costly or suffer from small throughput. Recently, a cost-effective method based on thin-film fracture that can be used as a template for NW fabrication was suggested. Here, a way to integrate NWs between microcontacts is demonstrated. Different geometries of microstructured photoresist formed by using standard photolithography are analyzed. Surprisingly, a very simple "stripe" geometry is found to yield highly reproducible fracture patterns, which are convenient templates for fault-tolerant NW fabrication. Microchips containing integrated Au, Pd, Ni, and Ti NWs and their suitability for studies of conductivity and oxidation behavior are reported, and their suitability as a hydrogen sensor is investigated. Details of the fabrication process are also discussed.