Electrical and optoelectronic anisotropy and surface electron accumulation in ReS nanostructures.

Two interesting electronic transport properties including in-plane anisotropy and nonhomogeneous carrier distribution were observed in ReS nanoflakes. The electrical conductivity defined by the current parallel to the -axis (‖) is 32 times higher than that perpendicular to the -axis (⊥). Similar anisotropy was also observed in optoelectronic properties in which the ratio of responsivity ‖ to ⊥ reaches 20.

Xenon gas field ion source from a single-atom tip.

Focused ion beam (FIB) systems have become powerful diagnostic and modification tools for nanoscience and nanotechnology. Gas field ion sources (GFISs) built from atomic-size emitters offer the highest brightness among all ion sources and thus can improve the spatial resolution of FIB systems. Here we show that the Ir/W(111) single-atom tip (SAT) can emit high-brightness Xe ion beams with a high current stability.

Nickel-containing nano-sized islands grown on Ge(111)-c(2 × 8) and Ag/Ge(111)-(√3 × √3) surfaces.

The formation of nano-islands on both a Ge(111)-c(2 × 8) surface and an Ag/Ge(111)-(√3 × √3) surface evaporated with 0.1 ML Ni was investigated by scanning tunneling microscopy (STM). We have noticed that at temperatures lower than 670 K, the reaction between Ni and the individual substrate surfaces proceeds to form different structures: flat-topped islands with a 2√7 × 2√7 or a 3 × 3 reconstruction on the Ni/Ge(111)-c(2 × 8) surface vs.

Structure of Co-2 × 2 nanoislands grown on Ag/Ge(111)-√3 × √3 surface studied by scanning tunneling microscopy.

We have found that Co-2 × 2 islands grown on an Ag/Ge(111)-√3 × √3 surface have hcp structure with the (11-20) orientation. The island evolution involves transformation of the unit cell shape from parallelogram into rectangular, which is accompanied by the island shape transformation from hexagonal into stripe-like. Identified are two crystallographic directions for the island growth, the pseudo-[0001] and the pseudo-[1-100].

Fabrication of CoPt ultra-sharp single atom tips.

Two kinds of new nano tips with potential to magnetic application are fabricated. One is a PtCo alloy pyramidal tip formed by surface faceting, the other is a Pt based Co tip formed by the epitaxy with a proper growth mode. Ultra high vacuum-field ion microscopy with atomic resolution is used to investigate the atomic structures of the tip apex after various sharpen treatments.

Size control of Co islands grown on √3 x √3-Ag/Ge(111) surface.

The growth of uniform nanostructures requires simple and reproducible ways to control the size. It is found that Co atoms can form two-dimensional structural islands on √3 x √3-Ag/Ge(111) surfaces. Temperature and Co coverage are two factors to modulate the island size.

Molecular structures of dicarboxylated viologens on a Cu(100) surface during an ongoing charge transfer reaction.

Molecular structures of dicarboxylated viologens (1,1'-bis (7-carboxyheptyl)-4,4'-bipyridinium dibromide molecules, V-(C(7)-COOH)(2)) on a Cu(100) surface are studied by means of in situ scanning tunneling microscopy (STM) in combination with cyclic voltammetry (CV). Self-assembled monolayers of adsorbed dicarboxylated viologens form during an ongoing charge transfer reaction. Mainly six structures of the organic molecules are observed, including a dot array, metastable phases, stripe patterns, a closed stacking stripe pattern, chloride desorption, and a dimer phase.

A single-atom sharp iridium tip as an emitter of gas field ion sources.

We report a reliable method for preparing a pure Ir single-atom tip by thermal treatment in oxygen. The atomic structure of the tip apex and its ion emission characteristics are investigated with field ion microscopy. We have shown that the Ir single-atom tip can be a good field ion emitter, capable of emitting a variety of gas ion beams, such as He+, H2+, N2+, and O2+, with high brightness and stability.

Reconstructed structures of nanosized co islands on Ag/Ge(111) mean square root of 3 x mean square root of 3 surfaces.

Structural evolution of Co/Ag/Ge(111) at high temperatures was studied by using scanning tunneling microscopy and low energy electron diffraction. The mean square root of 3 x mean square root of 3-Ag layer between the substrate Ge( 11) and Co adatoms can avoid the formation of Co-Ge compounds below 800 K. The Co atoms nucleate to form islands where mean square root of 13 x mean square root of 13 or 2 x 2 reconstructions were observed after annealing between 373 K and 737 K.