Anisotropy of Surface Energy and Thickness of the Surface Layer of Magnetic Nanostructures

In this work, we show how to calculate the surface energy anisotropy and the thickness of the surface layer of some magnetic nanostructures. As an example, the minerals of magnetite, ulvespineli, ilmenite andpseudobrukite, which have different crystal structures, are considered.

Templated dewetting of single-crystal sub-millimeter-long nanowires and on-chip silicon circuits

Large-scale, defect-free, micro- and nano-circuits with controlled inter-connections represent the nexus between electronic and photonic components. However, their fabrication over large scales often requires demanding procedures that are hardly scalable. Here we synthesize arrays of parallel ultra-long (up to 0.75 mm), monocrystalline, silicon-based nano-wires and complex, connected circuits exploiting low-resolution etching and annealing of thin silicon films on insulator. Phase field simulations reveal that crystal faceting and stabilization of the wires against breaking is due to surface energy anisotropy. Wires splitting, inter-connections and direction are independently managed by engineering the dewetting fronts and exploiting the spontaneous formation of kinks. Finally, we fabricate field-effect transistors with state-of-the-art trans-conductance and electron mobility. Beyond the first experimental evidence of controlled dewetting of patches featuring a record aspect ratio of $$\sim$$~1/60000 and self-assembled $$\sim$$~mm long nano-wires, our method constitutes a distinct and promising approach for the deterministic implementation of atomically-smooth, mono-crystalline electronic and photonic circuits.

Ab Initio Calculations of Absolute Surface Energies of Clean and Hydrogen Covered 3C-SiC(001), (110) and (111) Surfaces

The absolute surface energies of three major low index surfaces of cubic silicon carbide (3C-SiC) are determined by first-principles density functional theory calculations. Calculations show that among clean 3C-SiC surfaces the Si-terminated 3C-SiC(001)-(3x2) surface has the lowest energy. The second and third lowest energy surfaces are the Si-terminated 3C-SiC(111)-(√3x√3) surface and the nonreconstructed 3C-SiC(110) surface. Hydrogen passivation greatly reduces both the absolute surface energies of the low index 3C-SiC surfaces and the surface energy anisotropy. In particular, the surface energies of fully passivated 3C-SiC(110) and (111) surfaces become indistinguishable at hydrogen-rich deposition conditions.