Bridgeman technique
Encyclopedia
The Bridgman–Stockbarger technique is named after Harvard physicist Percy Williams Bridgman
and MIT physicist Donald C. Stockbarger (1895 - 1952). They are two similar methods primarily used for growing single crystal
ingot
s (boules
), but which can be used for solidifying polycrystalline ingots as well.
The methods involve heating polycrystalline material above its melting point and slowly cooling it from one end of its container, where a seed crystal
is located. A single crystal of the same crystallographic orientation as the seed material is grown on the seed and is progressively formed along the length of the container. The process can be carried out in a horizontal or vertical geometry.
The Bridgman method is a popular way of producing certain semiconductor
crystals for which the Czochralski process
is more difficult, such as gallium arsenide.
The difference between the Bridgman technique and Stockbarger technique is subtle: while a temperature gradient is already in place for the Bridgman technique, the Stockbarger technique requires pulling the boat through a temperature gradient to grow the desired single crystal.
When seed crystals are not employed as described above, polycrystalline ingots can be produced from a feedstock consisting of rods, chunks, or any irregularly shaped pieces once they are melted and allowed to resolidify. The resultant microstructures of the ingots so obtained are characteristic of directionally solidified metals and alloys with their aligned grains.
Percy Williams Bridgman
Percy Williams Bridgman was an American physicist who won the 1946 Nobel Prize in Physics for his work on the physics of high pressures. He also wrote extensively on the scientific method and on other aspects of the philosophy of science.- Biography :Bridgman entered Harvard University in 1900,...
and MIT physicist Donald C. Stockbarger (1895 - 1952). They are two similar methods primarily used for growing single crystal
Single crystal
A single crystal or monocrystalline solid is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries...
ingot
Ingot
An ingot is a material, usually metal, that is cast into a shape suitable for further processing. Non-metallic and semiconductor materials prepared in bulk form may also be referred to as ingots, particularly when cast by mold based methods.-Uses:...
s (boules
Boule (crystal)
A boule is a single-crystal ingot produced by synthetic means. A boule of silicon is the starting material for most of the integrated circuits used today....
), but which can be used for solidifying polycrystalline ingots as well.
The methods involve heating polycrystalline material above its melting point and slowly cooling it from one end of its container, where a seed crystal
Seed crystal
A seed crystal is a small piece of single crystal/polycrystal material from which a large crystal of the same material typically is to be grown...
is located. A single crystal of the same crystallographic orientation as the seed material is grown on the seed and is progressively formed along the length of the container. The process can be carried out in a horizontal or vertical geometry.
The Bridgman method is a popular way of producing certain semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
crystals for which the Czochralski process
Czochralski process
The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors , metals , salts, and synthetic gemstones...
is more difficult, such as gallium arsenide.
The difference between the Bridgman technique and Stockbarger technique is subtle: while a temperature gradient is already in place for the Bridgman technique, the Stockbarger technique requires pulling the boat through a temperature gradient to grow the desired single crystal.
When seed crystals are not employed as described above, polycrystalline ingots can be produced from a feedstock consisting of rods, chunks, or any irregularly shaped pieces once they are melted and allowed to resolidify. The resultant microstructures of the ingots so obtained are characteristic of directionally solidified metals and alloys with their aligned grains.
See also
- Czochralski processCzochralski processThe Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors , metals , salts, and synthetic gemstones...
- Float-zone siliconFloat-zone siliconFloat-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 configuration molten silicon has sufficient surface tension to...
- Micro-Pulling-DownMicro-pulling-down-Basics:The micro-pulling-down method is a crystal growth technique based on continuous transport of the melted substance through micro-channel made in a crucible bottom. Continuous solidification of the melt is progressed on a liquid/solid interface positioned under the crucible...
- Laser-heated pedestal growthLaser-heated pedestal growthLaser-heated pedestal growth is a crystal growth technique. The technique can be viewed as a miniature floating zone, where the heat source is replaced by a powerful CO2 or YAG laser...