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As fabrication and positioning of micro- and nanocrystals grow in importance in a wide range technological applications, there is an increasing requirement for the development of a shared technological platform that is able to process materials from solutions on large areas. Here, the application of lithographically controlled wetting (LCW) for the manipulation and positioning of single crystals directly on devices is reported. In the LCW, a stamp, consisting of a metallic grid, is positioned in contact with a liquid thin film spread on a substrate; under these conditions, the capillary forces pin the solution to the stamp protrusions, thus splitting the continuous film in separated droplets or channels. As the solvent evaporates and the solution reaches the saturation, the solute precipitates onto the substrate within the menisci, giving rise to a structured thin film, in correspondence of the protrusion of the stamp. The possibility to achieve a patterning of crystals of conjugated molecules with a defined shape and with controlled size directly on device is demonstrated and pattern of crystals are investigated using polarized optical microscopy, atomic force microscopy, X-ray diffraction; they are also electrically characterized. [ABSTRACT FROM AUTHOR]

The structure (size, shape, orientation) of CoPt alloy islands formed on NaCl(001) substrates was investigated using grazing-incidence small-angle X-ray scattering (GISAXS) combined with electron and X-ray diffraction and transmission electron microscopy. Co50Pt50 and Co25Pt75 islands formed at 473 K by co-deposition of Co and Pt species are oriented along the [001] direction, and their shapes are well described as truncated spheres with lateral sizes of around 4-5 nm. In contrast, using the same Co and Pt atomic fluxes, co-deposition at 673 K leads to the formation of strongly enriched Pt islands with larger sizes, and different orientations and shapes. The Pt enrichment is attributed to a large increase in the difference between the Co and Pt condensation coefficients with deposition temperature. Surprisingly, for the island assemblies formed at 673 K, the GISAXS patterns are dominated by the scattered intensities of the [001]- oriented islands with a truncated octahedron shape, thus masking the contributions of the [111]- and [110]-oriented islands which can exhibit larger sizes. [ABSTRACT FROM AUTHOR]

We have used confocal micro Raman spectroscopy, atomic force microscopy (AFM), and x-ray diffraction (XRD) to investigate pentacene films obtained by vacuum deposition on SiO2 substrates. These methods allow us to follow the evolution of lattice structure, vibrational dynamics, and crystal morphology during the growth from monolayer, to TF, and, finally, to bulk crystal. The Raman measurements, supported by the AFM and XRD data, indicate that the film morphology depends on the deposition rate. High deposition rates yield two-dimensional nucleation and quasi-layer-by-layer growth of the T-F form only. Low rates yield three-dimensional nucleation and growth, with phase mixing occurring in sufficiently thick films, where the T-F form is accompanied by the "high-temperature" bulk phase. Our general findings are consistent with those of previous work. However, the Raman measurements, supported by lattice dynamics calculations, provide additional insight into the nature of the TFs, showing that their characteristic spectra originate from a loss of dynamical correlation between adjacent layers. [ABSTRACT FROM AUTHOR]