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Several synthesis methods are known for SiNWs and these can be broadly divided into methods which start with bulk silicon and remove material to yield nanowires, also known as top-down synthesis, and methods which use a chemical or vapor precursor to build nanowires in a process generally considered to be bottom-up synthesis.
The Stöber process is a chemical process used to prepare silica (SiO 2) particles [1] of controllable and uniform size [2] for applications in materials science.It was pioneering [3] when it was reported by Werner Stöber and his team in 1968, [1] and remains today the most widely used wet chemistry synthetic approach to silica nanoparticles. [3]
One method to prepare silicon nanotubes is using a reactor employing an electric arc without the use of any catalyst. [4] To ensure purity, the reactor is evacuated and filled with the nonreactive noble gas argon. The actual formation of the nanotubes relies on the process of chemical vapor deposition. [5]
The method is used for the fabrication of metal oxides, especially the oxides of silicon (Si) and titanium (Ti). The process involves conversion of monomers in solution into a colloidal solution ( sol ) that acts as the precursor for an integrated network (or gel ) of either discrete particles or network polymers .
Most synthesis techniques use a bottom-up approach. Initial synthesis via either method may often be followed by a nanowire thermal treatment step, often involving a form of self-limiting oxidation, to fine tune the size and aspect ratio of the structures. [7] After the bottom-up synthesis, nanowires can be integrated using pick-and-place ...
SiHCl 3 → Si + Cl 2 + HCl SiH 4 → Si + 2 H 2. This reaction is usually performed in LPCVD systems, with either pure silane feedstock, or a solution of silane with 70–80% nitrogen. Temperatures between 600 and 650 °C and pressures between 25 and 150 Pa yield a growth rate between 10 and 20 nm per minute.
The vapor–liquid–solid method (VLS) is a mechanism for the growth of one-dimensional structures, such as nanowires, from chemical vapor deposition. The growth of a crystal through direct adsorption of a gas phase on to a solid surface is generally very slow.
The direct process, also called the direct synthesis, Rochow process, and Müller-Rochow process is the most common technology for preparing organosilicon compounds on an industrial scale. It was first reported independently by Eugene G. Rochow and Richard Müller in the 1940s.