Localized Growth of Silicon Oxide Nanowires by Micro‐Afterglow Oxidation

Abstract

Silicon oxide nanowires are synthesised below 523 K by a non‐VLS mechanism on different substrates: Fe‐0.5 wt.‐%Si and Fe‐1.5 wt.‐%Si alloys and silicon wafers coated or not by 30‐nm thick coatings of iron. An Ar‐O2 micro‐afterglow is used to feed the substrate with oxidising species over an area of ≈2 mm2. In this area, circular bundles of nanowires appear after 15 min and are randomly distributed. Each bundle diameter increases with time and reaches 50 µm. After several hours, bundles overlap and give a continuous carpet of nanowires. TEM analyses show that no iron is found in the nanowires, whatever the substrate. A growth mechanism, based on the emergence of a surface defect is proposed.

Nanostructures design by plasma afterglow-assisted oxidation of iron–copper thin films

“…Resorting to non-equilibrium media like plasmas is known as being a way to provide a part of the total energy under a non-thermal form [11,12]. Plasma synthesis of metal oxide nanostructures was widely investigated [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In direct low-pressure plasma processes, sputtering mechanisms can be partly responsible for the growth of nanostructures [13][14][15].…”

“…They are more active than ground state oxygen at low temperature because of the extra amount of energy coming from dissociation or excitation. Oxidation of metals in these conditions promotes the growth of oxide nanostructures [21][22][23][24][25][26].…”

Synthesis of RuO 2 nanowires from Ru thin films by atmospheric pressure micro-post-discharge

“…A transient heat transfer model, developed in a former work of ours (see reference [15] for a complete description of the model) was used to estimate the surface temperature. A 0.5 mm-thick cylindrical substrate (14 mm in diameter) made of fused silica and covered by a 900 nm-thick Ru layer was modelled.…”

“…A 0.5 mm-thick cylindrical substrate (14 mm in diameter) made of fused silica and covered by a 900 nm-thick Ru layer was modelled. The temperature distribution in the microafterglow was determined from the OH (A 2 Σ + ; v′ = 0 − X 2 Π; v″ = 0) rotational spectrum recorded at 306.4 nm by optical emission spectroscopy with an iCCD camera (see [15] for details). The maximum value was found to be 1600 K.…”

“…The corresponding growth mechanism was already observed in the synthesis of localised concentric rings of silica nanowires on silicon wafers [15]. Then, two types of oxides have to be considered depending on whether they are passive or not.…”