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The temporal shape evolution in glancing angle deposition was examined for a-Ge nanocolumns on honeycomb templates. The column shape formation is closely related to the particular stage of deposition and two shape regions were observed. (1) A broadening shape develops in the initial stage. Interdistance deposits were found to result from insufficient shadowing of the early nanostructures. On top of the nanocolumns, a characteristic cap is observed, which results from next-neighbor shadowing. (2) When the equilibrium cross-section shape is reached, a columnar region with parallel border planes follows. The shape of the cross-section can be tuned from triangular to hexagonal/round by adjusting the honeycomb lattice periodicity and the deposition angle. Based on quantitative investing on the axial sizes of the shape regions, conclusions regarding the influencing growth processes in glancing angle deposition on pre-patterned substrates are drawn. [ABSTRACT FROM AUTHOR]

Modification of nanoscale surface topography is inherent to low-energy ion beam erosion processes and is one of the most important fields of nanotechnology. In this report a comprehensive study of surface smoothing and self-organized pattern formation on Ge(100) by using different noble gases ion beam erosion is presented. The investigations focus on low ion energies (⩽ 2000 eV) and include the entire range of ion incidence angles. It is found that for ions (Ne, Ar) with masses lower than the mass of the Ge target atoms, no pattern formation occurs and surface smoothing is observed for all angles of ion incidence. In contrast, for erosion with higher mass ions (Kr, Xe), ripple formation starts at incidence angles of about 65° depending on ion energy. At smaller incident angles surface smoothing occurs again. Investigations of the surface dynamics for specific ion incidence angles by changing the ion fluence over two orders of magnitude gives a clear evidence for coarsening and faceting of the surface pattern. Both observations indicate that gradient-dependent sputtering and reflection of primary ions play crucial role in the pattern evolution, just at the lowest accessible fluences. The results are discussed in relation to recently proposed redistributive or stress-induced models for pattern formation. In addition, it is argued that a large angular variation of the sputter yield and reflected primary ions can significantly contribute to pattern formation and evolution as nonlinear and non-local processes as supported by simulation of sputtering and ion reflection. [ABSTRACT FROM AUTHOR]

Growth of Ge2Sb2Te5 phase-change films on flexible polyimide substrates by pulsed laser deposition (PLD) is demonstrated. The effect of annealing temperature on the crystalline nature of the films was studied. A decrease of (200) lattice plane distance with the increase of annealing temperature was revealed for the films grown on both polyimide and Si substrates, which was related to tensile stress in the crystallized films. Optical reflectivity measurements showed a high reflectivity contrast between full crystalline and amorphous films. The results indicate an excellent potential for applications of these PLD-deposited Ge2Sb2Te5 films on flexible polyimide substrates in optical data storage. [ABSTRACT FROM AUTHOR]

The energy and angular distributions of scattered and sputtered particles produced by ion beam sputtering of a Ge target under variation of geometrical (incidence angle of primary ions and emission angle of secondary particles) and ion parameters (ion species (Ar, Xe) and energy (0.5-1.5keV) are presented. Several sets of Ge thin films are deposited and their thickness is measured by profilometry to determine the angular particle flux distribution of the sputtered particles. The particle flux distributions are of cosine-like shape and tilted in forward direction and the tilt of the maximum position increases with decreasing energy of the primary ions and increasing incidence angle. The energy distributions of the sputtered and the scattered ions are measured with an energy-selective mass spectrometer. The average energy of the sputtered ions increases with increasing incidence angle of the primary ions and with increasing emission angle, but is nearly unaffected by the species of the primary ions and their energy. The energy distribution of the scattered Ar ions reveals high energetic maxima that originate in direct scattering between Ar/Ge and Ar/Ar and which shift with increasing emission angle to higher energies. For Xe ion bombardment, there are only maxima for Xe/Xe scattering observed. All experimental data are compared with Monte Carlo simulations done with the well-known TRIM.SP code. [ABSTRACT FROM AUTHOR]