Production of self-aligned metal nanocolumns embedded in an oxide matrix film

Abstract

Self-aligned silver nanocolumns embedded in amorphous Al2O3 matrix are produced by alternate pulsed laser deposition at room temperature in a single step process. The morphology and the spatial distribution have been investigated by standard, high resolution, and scanning transmission electron microscopy. Polycrystalline nanocolumns having diameters close to 3nm and heights up to 7nm are all oriented perpendicular to the substrate surface. The self-alignment of the nanocolumns is the consequence of the deposition of consecutive layers of Ag nanoparticles using the first layer as template for the ordered growth of the nanocolumns. Control over the density, diameter and height of the nanocolumns is achievable by tailoring the deposition sequence.

Acoustic Vibration Modes and Electron–Lattice Coupling in Self-Assembled Silver Nanocolumns

“…In particular, silver nanocolumns (NCls) embedded in amorphous Al 2 O 3 matrix (a-Al 2 O 3 ) have recently been fabricated by self-assembling using alternate pulsed laser deposition. 17 This technique has proven its potential for the production of silver nanocolumns oriented perpendicularly to the substrate with low size and shape dispersion. Earlier reported extinction spectra of these NCls exhibit two distinct optical resonances due to the transverse and longitudinal surface plasmons.…”

Surface Plasmons and Vibrations of Self-Assembled Silver Nanocolumns

“…To identify the acoustic vibration modes responsible for the measured Raman signal, we have performed molecular dynamic (MD) simulations. 37 Because the elastic properties of monocrystalline silver are strongly dependent on crystallographic direction, 36 and in the present case the NCls are polycrystalline, 17 we have assumed isotropic elasticity and we used sound velocities V L ) 3750 m/s and V T ) 1740 m/s obtained by averaging the elastic constants of silver over all directions. We also assumed that the NCls have a prolate spheroidal shape and are free-standing; that is, the a-Al 2 O 3 host has no influence on the vibrations.…”

“…Because the aspect ratio of the NCls is H/D NCl ) 2.5 ( 0.3, shape fluctuations are not directly responsible for inhomogeneous broadening of the Raman band (Figures 3 and 5). However, taking into account the measured dispersion 17 in the NCl's diameter, D NCl min ) 2.5 nm and D NCl max ) 2.9 nm and using S ) 0.8, one can easily estimate that the frequency of the SLMs (l ) 2, m ) (2) falls in the range of 18.5-21 cm -1 . So, one expects a shift of the Raman band toward lower frequencies when decreasing the excitation wavelength due to selection of NCls with smaller aspect ratios (i.e., larger D NCl values).…”

Sculpting nanometer-sized light landscape with plasmonic nanocolumns

“…26 Recently, self-assembled silver nanocolumns ͑NCls͒ have been fabricated using pulsed laser deposition. 27 These nanostructures are composed of small silver NCls ͑diameter 2 Ͻ D Ͻ 3 nm and height 6 Ͻ H Ͻ 15 nm͒ aligned perpendicularly to the substrate with an interparticle spacing comparable to the diameter of the NCls, thus having much smaller features than the ones used for earlier calculations. 26 The absorption cross section of these structures exhibits two bands with a smaller spectral splitting than expected in isolated silver NCls due to interparticle electromagnetic coupling.…”

“…[29][30][31] The aim of this paper is to calculate the far-field and near-field effects produced by the densely packed array of silver NCls whose production and structural properties were reported elsewhere. 27 The model, based on the discrete di-pole approximation ͑DDA͒, [32][33][34] is first used to fit the experimentally measured far-field response. The role of the dimension of the array and the detailed shape of the NCls ͑perfect or shrinked rods, with or without dispersion͒ is first studied separately.…”