The micro-pulling-down (μ-PD) method is a
crystal growth
A crystal is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. Crystal growth is a major stage of a crystallization process, and consists of the ...
technique based on continuous transport of the melted substance through micro-channel(s) made in a
crucible
A crucible is a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures. While crucibles were historically usually made from clay, they can be made from any material that withstands te ...
bottom. Continuous
solidification
Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liqu ...
of the melt is progressed on a liquid/solid interface positioned under the crucible. In a steady state, both the melt and the crystal are pulled-down with a constant (but generally different)
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity i ...
.
Many different types of crystal are grown by this technique, including
Y3Al5O12,
Si,
Si-Ge,
LiNbO3,
α-Al2O3,
Y2O3,
Sc2O3,
LiF,
CaF2,
BaF2, etc.
Crystal growth routine
Standard routine procedure used in the growth of most of μ-PD crystals is well developed. The general stages of the growths include:
* Charging of the crucible with starting materials (mixture of powders)
* Heating of the crucible until starting materials in the crucible are completely melted
* Upward displacement of the seed until its contact with the meniscus or crucible
* Formation of the meniscus and partial melting of the seed top
* Correction of the shape of the meniscus through appropriate adjustment of crucible temperature and position of the seed crystal
* Crystal growth through pulling of the seed in downward direction
* Separation of the as grown crystal from the meniscus
* Cooling of the system (including the crystal and the crucible) to room temperature
See also
*
Crystal growth
A crystal is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. Crystal growth is a major stage of a crystallization process, and consists of the ...
*
Czochralski process
*
Float-zone silicon
Float-zone silicon is very pure silicon obtained by vertical zone melting. The process was developed at Bell Labs by Henry Theuerer in 1955 as a modification of a method developed by William Gardner Pfann for germanium. In the vertical configura ...
*
Flux method
*
Laser-heated pedestal growth
*
Shaping processes in crystal growth
Shaping processes in crystal growth are a collection of techniques for growing bulk crystals of a defined shape from a melt, usually by constraining the shape of the liquid meniscus by means of a mechanical shaper. Crystals are commonly grown as fi ...
*
Verneuil process
*
Lithium niobate
Lithium niobate () is a non-naturally-occurring salt consisting of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators and various other linea ...
*
Sapphire
Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sa ...
*
Scandium(III) oxide
*
Yttrium aluminium garnet
References
Chemical processes
Industrial processes
Semiconductor growth
Crystals
Methods of crystal growth
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