ZnO nanopillars have been electrodeposited epitaxially onto Au(111), Au(110) and Au(100) single-crystal substrates. The nanopillars grow with the same [0001] out-of-plane orientation on all three substrates. The in-plane orientation was probed by X-ray pole figure analysis. The pole figures had six peaks on Au(111) and twelve peaks on Au(110) and Au(100). Scanning electron microscopy revealed aligned hexagonal nanopillars of ZnO with an average grain size of 85 nm on Au(111). There were two sets of hexagonal grains with an average size of 85 nm on Au(110) and 95 nm on Au(100) that were rotated 90° with respect to each other. Rocking curve analysis showed that the ZnO on Au(100) had the smallest mosaic spread.

Half-metallic ferrimagnetic materials such as Fe(3)O(4) are of interest for use in spintronic devices. These devices exploit both the spin and charge of an electron in spin-dependent charge transport. Epitaxial thin films of Fe(3)O(4) have been grown on the three low-index planes of gold by electrodeposition. On Au(110), a [110] Fe(3)O(4) orientation that is aligned with the underlying Au(110) substrate is observed. Thin films on Au(100) grow with three different orientations: [100], [111], and [511]. On Au(111), both [111] and [511] orientations of Fe(3)O(4) are observed. The [511] orientations are the result of twinning on [111] planes. A polarization value of approximately -40% at the Fermi level was measured by spin-polarized photoemission at room temperature for a thin film on Au(111).

No abstract

Hybrid silicon capacitors have been successfully fabricated by attaching monolayers of redox-active molecules via self-assembly to ultrathin silicon dioxide layers. Capacitance, conductance, and cyclic voltammetric measurements have been used to characterize these capacitors. The presence of distinct capacitance and conductance peaks associated with oxidation and reduction of the monolayers at low gate voltages indicates discrete electron storage states for these capacitors, suggesting their feasibility in memory devices. The inherent molecular scalability and low-power operation coupled with existing silicon technology support the approach of hybrid molecule-silicon devices as a strong candidate for next generation electronic devices.

Structures formed by the electrodeposition of atomic layers of chalcogenides Se and Te, on Au(100) and Au(111), are described and compared. Each element, on each surface, forms a low coverage structure, consisting of atoms packed simply in high coordinate sites at distances just above their van der Waals diameter. As coverages are increased above this level, structures composed of chalcogenide atom chains or rings are formed. It is proposed that these chains or rings have significant molecular character, involving orbital overlap of adjacent chalcogenide atoms. Mechanisms are described to account for the formation of these chains and rings. Discussion is also presented concerning the appearance of triangular phase boundaries for both chalcogenides on Au(111). In the case of Se, isolated triangles, about 4-6 nm on a side are distributed across the surface, whereas a network of triangular phase boundaries is observed in the deposition of Te. The triangular phase boundaries in Se appear to result from the nucleation of domains in different threefold sites on Au(111). For Te, however, it is proposed that the triangular domains and phase boundaries are the result of Te atoms being too large to form an extended (Ίෆ 3XΊෆ 3)R30Њ structure.