On the origin of self-organization of SiO₂ nanodots deposited by CVD enhanced by atmospheric pressure remote microplasma

Abstract

The origin of organization of nanostructured silica coatings deposited on stainless steel substrates by remote microplasma at atmospheric pressure is investigated. We show by resorting to thermal camera measurements coupled with modelling that deposition, limited to a few seconds in time, occurs at low temperature (∼below 420 K) although the gas temperature may reach 1400 K. Raman analyses of deposited films with thicknesses below 1 µm show the presence of oxidized silicon bonded to the metallic surface. The origin of nanodots is explained as follows. Close to the microplasma nozzle, the concentration of oxidizing species and/or the temperature being high enough, a silica thin film is obtained, leading to ceramic–metallic oxide interface that leads to a Volmer–Weber growth mode and to the synthesis of 3D structures over long treatment times. Far from the nozzle, the reactivity decreasing, thin films get a plasma–polymer like behaviour which leads to a Franck–Van der Merwe growth mode and films with a higher density. Other nanostructures, made of hexagonal cells, are observed but remain unexplained.

Localized Growth of Silicon Oxide Nanowires by Micro‐Afterglow Oxidation

“…A detailed description of the experimental set‐up is provided in ref 25. Briefly, the atmospheric microwave plasma is created in a fused silica tube located in a 2.45 GHz resonant cavity.…”

“…The temperature (as defined in ref 27. for a non‐equilibrium medium) of the afterglow and its spatial distribution were determined by optical emission spectroscopy 25. Experimental measurements together with modelling allowed us to obtain an accurate estimation of the time evolution of the surface temperature.…”

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].…”

Reductant‐Free Synthesis of Silver Nanoparticles by Functionalized Hollow Doughnut Mesoporous Silica Nanoparticles for Preparation of Catalytic Nanoreactor

“…Both spectra of hd‐MSN‐NH 2 and Ag/hd‐MSN‐NH 2 exhibited the peak at 803 cm −1 that was assigned to the Si‐O−Si vibration .…”