Hallmark of quantum skipping in energy filtered lensless scanning electron microscopy

We simulate the electronic system of ejected electrons arising when a tip, positioned few 10 amp; 8201;nm away from a surface, is operated in the field emission regime. We find that, by repeated quantum reflections quantum skipping , electrons produced at the nanoscale primary site are able to reach the macroscopic environment surrounding the tip surface region. We observe the hallmark of quantum skipping in an energy filtered experiment that detects the spin of the ejected electron

Self-assembly of ultrafine nanolines upon Ho reaction with the Ge(001) surface

The reaction of the rare earth metal Ho with the Ge(001) surface at 440 °C has been studied by scanning tunneling microscopy (STM). The self-assembly of ultrafine nanolines growing along substrate 110 directions has been observed, and based on atomic resolution STM images, the authors propose a model of the nanolines and comment on their relationship to the very initial stages of growth of a hexagonal germanide structure. The authors further report the presence of nanoscale trenches associated with well-ordered lines of missing dimer defects and discuss the relationship of these to the nanolines. Their results have possible applications involving interconnects or templating in nanoscale devices, and additionally, may provide insight into the nucleation mechanism of coarser nanowires

Silicon overlayer growth on clean and hydrogen-terminated two-dimensional holmium silicide

The growth of silicon overlayers on both two-dimensional (2D) holmium silicide and hydrogen-terminated 2D holmium silicide grown on Si(111) has been investigated using scanning tunneling microscopy (STM). In the nonhydrogen-terminated case, the surface is heavily islanded, exhibiting the 7×7 and 2×1 silicon reconstructions. Growth on the hydrogen-terminated surface differs substantially, being better ordered and less heavily islanded. Growth mechanisms are proposed to explain these observed differences. STM data are also presented from the hydrogen-terminated 2D holmium silicide surface

Structural studies of two- and three-dimensional dysprosium silicides using medium-energy ion scattering

Medium-energy ion scattering has been used to determine the atomic structure of two-dimensional and three-dimensional (3D) dysprosium silicide films on the Si(1 1 1) surface. A quantitative study of the ion yield from the dysprosium has enabled the positions of the atoms in the top three layers of the Si(1 1 1)1×1–Dy to be precisely determined. For the case of the Si(1 1 1)(√3×√3)R30°–Dy 3D silicide surface the experimental blocking curves are in agreement with simulations for the structural model determined by surface X-ray diffraction for the Si(1 1 1)(√3×√3)R30°–Er 3D silicide surface. A contraction of 2.0±0.6% in the c-axis lattice constant compared to bulk dysprosium disilicide is found

A medium-energy ion scattering investigation of the structure and surface vibrations of two-dimensional YSi2 grown on Si(111)

Medium-energy ion scattering has been used to determine the atomic structure of two-dimensional yttrium silicide on silicon (1 1 1). A full quantitative analysis of the atomic positions of the Si atoms in the top bilayer yields a model similar to that previously suggested in the literature with a Si1–Si2 vertical spacing of 0.80 ± 0.03 Å, but with the Si bilayer relaxed slightly further away from the Y layer (Si2–Y vertical spacing of 1.89 ± 0.02 Å). Observing the effects of the top bilayer vibrations yields a model with significant enhancement

Trends and strain in the structures of two-dimensional rare-earth silicides studied using medium-energy ion scattering

The surface structures of the two-dimensional (2D) rare-earth (RE) silicides formed by Gd and Tm on Si(111) have been determined using medium-energy ion scattering (MEIS). These data have been taken together with those from earlier MEIS studies of the 2D silicides formed by Dy, Ho, Er, and Y to investigate the existence of trends in the structural parameters of this class of surfaces. It was found that the Si-RE bond length associated with the surface bilayer in the 2D silicides followed the same trend as the bond length in the bulk silicide compounds which is simply related to the size of the RE atom. In contrast, changes in the Si-RE layer spacing in the 2D silicides were found to be too large to be accounted for by a size effect alone. It was found that the strain that results from the expansion or compression of the overlayer to fit the Si(111) surface is compensated by changes in the Si-RE layer spacing. Finally, there is a systematic variation in the rumple of the surface bilayer in the 2D RE silicides which appears to increase with the magnitude of the lattice mismatch suggesting that strain in the overlayer results in a weakening of the Si-Si bond in the surface bilayer