We present a detailed study on the growth process of cupric oxide (CuO) nanowires by thermal oxidation. The morphology of nanowires, obtained at different oxidation temperatures and times, was determined. The diameter of nanowires was found to depend linear on temperature whereas the time dependence of their length is modeled by a parabolic law. The results suggest that CuO nanowires are formed as a result of the competition between grain boundary and lattice diffusion of Cu atoms across a ${\text{Cu}}_2\text{O}$ layer. Electrical characterization of the nanowires was also performed. A field effect transistor was produced with an isolated nanowire showing $p$ -type characteristics. The resistivity, mobility, and density of carriers were calculated. Nanowire growth by thermal oxidation is very simple and has great potential to be used for large scale production; this opens possibilities for various kinds of application.

We report the observation of an isolated charged impurity in graphene and present direct evidence of the close connection between the screening properties of a 2D electron system and the influence of the impurity on its electronic environment. Using scanning tunneling microscopy and Landau level spectroscopy, we demonstrate that in the presence of a magnetic field the strength of the impurity can be tuned by controlling the occupation of Landau-level states with a gate voltage. At low occupation the impurity is screened, becoming essentially invisible. Screening diminishes as states are filled until, for fully occupied Landau levels, the unscreened impurity significantly perturbs the spectrum in its vicinity. In this regime we report the first observation of Landau-level splitting into discrete states due to lifting the orbital degeneracy.

We report a chemically specific x-ray photoelectron diffraction (XPD) investigation using synchrotron radiation of the thermally induced growth of epitaxial graphene on the 6$H$-SiC(0001). The XPD results show that the buffer layer on the SiC(0001) surface is formed by two domain regions rotated by ${60}^{$\circ${}}$ with respect to each other. The experimental data supported by a comprehensive multiple scattering calculation approach indicates the existence of a long-range ripple due the $(6\sqrt{3}\ifmmode\times\else\texttimes\fi{}6\sqrt{3})R{30}^{$\circ${}}$ reconstruction, in addition to a local range buckling in the (0001) direction of the two sublattices that form the honeycomb structure of the buffer layer. This displacement supports the existence of an $s{p}^{2}$-to-$s{p}^{3}$ rehybridization in this layer. For the subsequent graphene layer this displacement is absent, which can explain several differences between the electronic structures of graphene and the buffer layer.