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Nanoscale contacts between metals and semiconductors are critical for further downscaling of electronic and optoelectronic devices. However, realizing nanocontacts poses significant challenges since conventional approaches to achieve ohmic contacts through Schottky barrier suppression are often inadequate. Here we report the realization and characterization of low n-type Schottky barriers (B0.35 eV) formed at epitaxial contacts between Au-In alloy catalytic particles and GaAs-nanowires. In comparison to previous studies, our detailed characterization, employing selective electrical contacts defined by high-precision electron beam lithography, reveals the barrier to occur directly and solely at the abrupt interface between the catalyst and nanowire. We attribute this lowest-to-date-reported Schottky barrier to a reduced density of pinning states (B10 17 m À 2 ) and the formation of an electric dipole layer at the epitaxial contacts. The insight into the physical mechanisms behind the observed lowenergy Schottky barrier may guide future efforts to engineer abrupt nanoscale electrical contacts with tailored electrical properties.

A simple approach for synthesis of palladium and silver nanostructures with readily adjustable morphologies was developed using galvanic electrochemical deposition, for application to surface-assisted laser desorption/ionization (SALDI) of small biological molecules. A range of fatty acids, triglycerides, carbohydrates, and antibiotics were investigated to assess the performance of the new materials. Intense analyte cations were generated from the galvanic surfaces upon UV laser irradiation such as potassium adducts for a film thickness <100 nm (originating from impurities of the electrolyte solution) and Pd and Ag cluster ions for films with a thickness >120 nm. Possible laser desorption/ionization mechanisms of these galvanic structures are discussed. The films exhibited self-organizing abilities and adjustable morphologies by changing electrochemical parameters. They did not require any stabilizing agents and were inexpensive and very easy to produce. SALDI analysis showed that the materials were stable under ambient conditions and analytical results with excellent measurement reproducibility and detection sensitivity similar to MALDI were obtained. Finally, we applied the galvanic surfaces to fast screening of natural oils with minimum sample preparation.

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A relationship is established between the growth rate of silicon whiskers and the solubility of the crystallizing substance in metal solvent particles. The effect of the whisker diameter on the growth rate is analyzed. The solubility of the solid phase is shown to drop as the particle size of the solvent decreases (its specific surface increases). The practical importance of these findings is discussed. v , µ m/s 1.5 1.0 0.5 0 Ag Cu Au Ni Pt Fig. 1. Growth rates of silicon whiskers at 1330 K for different metal solvents (at 1470 K for silver).

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In this paper, we report that under wetting conditions (or modes) of nanowire (NW) growth, when a nonplanar crystallization front emerges under a catalyst droplet, a shift in the three-phase line (TPL) of the vapor–liquid–crystal interface occurs under thermodynamically stable conditions when the angle with respect to the droplet surface, termed the growth angle, is fixed. The growth angle of the NWs is determined not from a geometrical perspective but on the basis of the physical aspects of the processes occurring around the TPL, revealing a size dependence caused by the influence of linear tension of the three-phase contact of a vapor–liquid crystal. The observed radial periodic instability of the NWs is described according to the size dependence of the thermodynamic growth angle, which induces negative feedback in the system. Under the influence of linear tension and positive feedback, the tips or needles of NWs can be formed.