The micro-pulling-down (μ-PD) method is a
crystal growth
Crystal growth is a major stage of a crystallization, crystallization process, and consists of the addition of new atoms, ions, or polymer strings into the characteristic arrangement of the crystalline lattice. The growth typically follows an ini ...
technique based on continuous transport of the melted substance through micro-channel(s) made in a
crucible
A crucible is a container in which metals or other substances may be melted or subjected to very high temperatures. Although crucibles have historically tended to be made out of clay, they can be made from any material that withstands temperat ...
bottom. Continuous
solidification
Freezing is a phase transition in which a liquid turns into a solid when its temperature is lowered below its freezing point.
For most substances, the melting and freezing points are the same temperature; however, certain substances possess dif ...
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 a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical q ...
.
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
Crystal growth is a major stage of a crystallization, crystallization process, and consists of the addition of new atoms, ions, or polymer strings into the characteristic arrangement of the crystalline lattice. The growth typically follows an ini ...
*
Czochralski process
The Czochralski method, also Czochralski technique or Czochralski process, is a method of crystal growth used to obtain single crystals (monocrystals) of semiconductors (e.g. silicon, germanium and gallium arsenide), metals (e.g. palladium, plati ...
*
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 configurat ...
*
Flux method
The flux method is a crystal growth method where starting materials are dissolved in a solvent (flux), and are precipitated out to form crystals of a desired compound. The flux lowers the melting point of the desired compound, analogous to a wet c ...
*
Laser-heated pedestal growth
Laser-heated pedestal growth (LHPG) or laser floating zone (LFZ) is a crystal growth technique. A narrow region of a crystal is melted with a powerful Carbon-dioxide laser, CO2 or Nd:YAG laser. The laser and hence the zone melting, floating zone, i ...
*
Shaping processes in crystal growth
*
Verneuil process
*
Lithium niobate
Lithium niobate () is a synthetic salt consisting of niobium, lithium
Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperatur ...
*
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, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon. The name ''sapphire ...
*
Scandium(III) oxide
*
Yttrium aluminium garnet
Yttrium aluminium garnet (YAG, Yttrium, Y3Aluminium, Al5Oxygen, O12) is a synthetic crystalline material of the garnet group. It is a Crystal system, cubic yttrium aluminium oxide phase, with other examples being YAlO3 (YAP) in a Crystal system, ...
References
Chemical processes
Industrial processes
Semiconductor growth
Crystals
Methods of crystal growth
{{science-stub