1. Formation kinetics of silicon solids in gas-phase reaction of silicon tetrahalide (SiCl4)

Silicon tetrachloride (SiCl4) is reduced by zinc vapor and solid silicon forms. The overall reaction is,
SiCl4 + 2Zn = Si + 2ZnCl2.
This reaction has been known as "zinc reduction reaction" and has been expected as a potential low-cost reaction route for solar-grade silicon.
However, due to the lack of important information, such as reaction paths and reaction rates, practical use of the reaction has been a challenge.

We investigate reaction kinetics of the zinc reduction reaction.
We have revealed that silicon materials with a variety of morphologies, for example, silicon nanowires, microparticles and silicon needles, form depending on reaction rates and conditions.

In addition, we have revealed several important aspects in this reaction, such as growth kinetics of Si wires, single-step production of b-doped Si wires, thermal aspects in growing Si wires and formation of mat of silicon nanowires.(Fig. 1)

In-situ observation of growth of silicon wires.

Single-step synthesis of boron -doped Si wires.

Temperature profile in rapidly growing silicon wires.

Synthesis of "cm2-scale" mat of silicon nanowires.


Fig. 1 Recent progresses in Silicon synthesis.
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