| Summary: | 碩士 === 國立中央大學 === 化學工程研究所 === 82 === The control of the growth front(melt/crystal interface) in the
vertical Bridgman(VB)crystal growth is necessary to growth a
crystal with desirable quality for device applic- ations.
Usually, a flat or slightly convex interface shape toward the
melt during crystal growth is most desirable for growing single
crystals with low defects. However, in prac- tice it is very
difficult to manipulate the melt and crystal temperature
distributions that lead to the desirable inter- face. Owing to
the complexity and invisibility of the system the control of
the growth front shape could be rather diffi- cult.As it is, an
effective interface control relies on a thorough understanding
of the interactions of solidification phenomena and ambient
thermal environments. Therefore, to study the VB crystal growth
systematically, direct observation of crystal growth in a
computer-controlled transparent multi- zone furnace and the
heat flow simulation are conducted. In the crystal growth
experiments, sodium nitrate is chosen as a model material.
Owing to the transparent melt and crystal, the growth front
during crystal growth in the transparent furnace with a
specified heating profile can be visualized.
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