Template-directed self-assembly of buried nanowires and the pearling instability

Abstract

The fabrication of more and more miniaturized electronic and photonic devices relies on new, ingenious methods for the fabrication of spatially controlled nanostructures. Examples are electronic devices based on semiconducting nanowires and photonic devices based on chains of metallic nanoclusters that guide light by coupled surface plasmons. In this contribution a template-directed ion beam synthesis of nanowires and regular nanocluster chains will be presented. As templates, V-grooves etched in (001)Si and subsequently oxidized are used. High fluence Ge + implantation is carried out into the SiO2 layer at 70 keV. Thereby, the implanted Ge enriches themselves in the Vgroove bottom to a critical amount, which may result in nanowire formation by nucleation, growth and coalescence during subsequent thermal treatment. TEM investigations indicate the formation of a nanowire buried in the SiO2 at the V-groove bottom.Kinetic lattice Monte Carlo simulations of the nanowire formation process were performed in order to understand the phase separation mechanism and results are compared to TEM images. Furthermore, it is shown that even ideal nanowires show a instability and form during long-lasting annealing equal-spaced and equal-sized nanoclusters ("nanocluster chains") by self-organization.

Ion and electron irradiation-induced effects in nanostructured materials

“…514 They can also be made of all classes of materials and may not be circular but also flattened in cross section ͑nanobelts or nanoribbons͒. 509 Hence, in contrast to the case of carbon nanotubes, it is hardly possible to give almost any common characteristics of how NWs behave under irradiation, with the obvious exception that surface effects can be expected to be significant.…”

“…563 Another less direct approach to form NWs lying on substrates was introduced by in Ref. 514. V-shaped grooves on Si were first formed with anisotropic etching.…”

“…At long annealing times or high temperatures, it would break up into individual nanoclusters due to the Rayleigh ͑pearling͒ instability. 514,565 This effect could, however, also be beneficial in itself, as it could be used to produce an array of roughly equisized and equidistant nanoclusters. 514 We note that the Rayleigh instability 565 applies to all NWs, and any NW can be expected to break down into isolated clusters if the annealing temperature is too high compared to the width and surface/interface energy of the wire material.…”

A tangent-plane marker-particle method for the computation of three-dimensional solid surfaces evolving by surface diffusion on a substrate

“…2, we plot the normal surface velocity V n versus time computed using N ¼ 2025 for the two grid-invariant marker particles at y ¼ 0 and y ¼ L. The growth rates are found by an exponential fit to be À87. 26 and À87.28. The exponential fits are also plotted in Fig.…”

“…Rayleigh instability of supported copper, gold and platinum nanowires was experimentally demonstrated [37,17,45]. The kinetic Monte Carlo simulations of instability development due to axisymmetric perturbation (in a free wire) were performed by Muller et al [26] and gave predictions consistent with the Nichols and Mullins analysis.…”