Natural Formation of Nanostructures from Fundamentals in Metal Heteroepitaxy to Applications in Optics and Biomaterials Science

Abstract

The tailoring of nanostructures by the use of vapor deposition techniques opens up new opportunities to engineer innovative materials and devices in different fields, including optoelectronics and biomaterials. This review elucidates recent advances in the understanding of heteroepitaxy exemplifying the growth of copper on Ni(100) and the growth of para-hexaphenyl on GaAs. Although copper on nickel belongs to the simplest systems, unprecedented morphologies arise, such as ramified islands on a square lattice and strain relief by internal faceting. The elongated para-hexaphenyl crystallites formed on GaAs(001) exhibit a polarized blue light emission, which is a basis for developing organic diode lasers. Anisotropic thin film morphologies are also realized by oblique incidence deposition of noncentrosymmetric organic molecules onto amorphous substrates. Using the frequency doubling of light, it has been demonstrated for the first time that the films not only are anisotropic but also exhibit a preferential orientation of the molecules. Germanium nanopyramids epitaxially grown on Si(001) provide evidence that a well-defined nanopatterned substrate alters the contact angles of water, the protein adsorption and activity, as well as the cell behavior. These results are a milestone in structural biocompatibility on the nanometer scale.