Zone melting

zone refiningfloating zonefloating zone crystal growthfloating zone methodfloating zone processindirect-heating floating zonemeltzone-melting
Zone melting (or zone refining or floating zone process or travelling melting zone) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is melted, and this molten zone is moved along the crystal.wikipedia
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William Gardner Pfann

William G. PfannBill Pfann
Zone refining was invented by John Desmond Bernal and further developed by William Gardner Pfann in Bell Labs as a method to prepare high purity materials, mainly semiconductors, for manufacturing transistors.
Pfann is known for his development of zone melting which is essential to the semiconductor industry.

Bell Labs

Bell LaboratoriesBell Telephone LaboratoriesAT&T Bell Laboratories
Zone refining was invented by John Desmond Bernal and further developed by William Gardner Pfann in Bell Labs as a method to prepare high purity materials, mainly semiconductors, for manufacturing transistors.
In 1952, William Gardner Pfann revealed the method of zone melting which enabled semiconductor purification and level doping.

Germanium

GeGe diodesGerman
Its first commercial use was in germanium, refined to one atom of impurity per ten billion, but the process can be extended to virtually any solute-solvent system having an appreciable concentration difference between solid and liquid phases at equilibrium.
Zone refining techniques have led to the production of crystalline germanium for semiconductors that has an impurity of only one part in 10 10,

Float-zone silicon

float-zonefloat-zone growth
The bulk charge carrier lifetime in float-zone silicon is the highest among various manufacturing processes.
Float-zone silicon is very pure silicon obtained by vertical zone melting.

Fractional freezing

Freeze distillationfreeze-distilledpartially freezing
It can be done by partial melting of a solid, for example in zone refining of silicon or metals, or by partial crystallization of a liquid, as in freeze distillation, also called normal freezing or progressive freezing.

Boron

Bboron-10 10 B
For example, in germanium, pentavalent elements of group V such as antimony and arsenic produce negative (n-type) conduction and the trivalent elements of group III such as aluminum and boron produce positive (p-type) conduction.
Ultrapure boron for use in the semiconductor industry is produced by the decomposition of diborane at high temperatures and then further purified by the zone melting or Czochralski processes.

Silicon

Sisilicon revolutionsilicium
This technique is also used for the preparation of silicon for use in computer chips.
The spongy pieces of silicon thus produced are melted and then grown to form cylindrical single crystals, before being purified by zone refining.

Laser-heated pedestal growth

Laser heated pedestal growth
The laser and hence the floating zone, is moved along the crystal.

Wafer (electronics)

wafersilicon waferwafers
In this process, a cylindrical ingot of high purity monocrystalline semiconductor, such as silicon or germanium, called a boule, is formed by pulling a seed crystal from a melt.

Melting point

freezing pointmelting temperaturemelting

J. D. Bernal

John Desmond BernalJ.D. BernalJohn Bernal
Zone refining was invented by John Desmond Bernal and further developed by William Gardner Pfann in Bell Labs as a method to prepare high purity materials, mainly semiconductors, for manufacturing transistors.

Transistor

transistorstransistorizedsilicon transistor
Zone refining was invented by John Desmond Bernal and further developed by William Gardner Pfann in Bell Labs as a method to prepare high purity materials, mainly semiconductors, for manufacturing transistors.

Solution

solutesolutessolutions
Its first commercial use was in germanium, refined to one atom of impurity per ten billion, but the process can be extended to virtually any solute-solvent system having an appreciable concentration difference between solid and liquid phases at equilibrium.

Solvent

solventsorganic solventorganic solvents
Its first commercial use was in germanium, refined to one atom of impurity per ten billion, but the process can be extended to virtually any solute-solvent system having an appreciable concentration difference between solid and liquid phases at equilibrium.

Boule (crystal)

boulesboulecrystal boules
Thus, by passing a crystal boule through a thin section of furnace very slowly, such that only a small region of the boule is molten at any time, the impurities will be segregated at the end of the crystal.

Single crystal

single-crystalsingle crystalsmonocrystalline
Because of the lack of impurities in the leftover regions which solidify, the boule can grow as a perfect single crystal if a seed crystal is placed at the base to initiate a chosen direction of crystal growth.

Seed crystal

Seedingnucleiseed
Because of the lack of impurities in the leftover regions which solidify, the boule can grow as a perfect single crystal if a seed crystal is placed at the base to initiate a chosen direction of crystal growth.

Crystal

crystallinecrystalscrystalline solid
In zone leveling, the objective is to distribute solute evenly throughout the purified material, which may be sought in the form of a single crystal.

Diode

diodessemiconductor diodegermanium diode
For example, in the preparation of a transistor or diode semiconductor, an ingot of germanium is first purified by zone refining.

Semiconductor

semiconductorssemiconductingsemiconductor material
Zone refining was invented by John Desmond Bernal and further developed by William Gardner Pfann in Bell Labs as a method to prepare high purity materials, mainly semiconductors, for manufacturing transistors. For example, in the preparation of a transistor or diode semiconductor, an ingot of germanium is first purified by zone refining.

Antimony

Sbantimonialantimonium
For example, in germanium, pentavalent elements of group V such as antimony and arsenic produce negative (n-type) conduction and the trivalent elements of group III such as aluminum and boron produce positive (p-type) conduction. Then a small amount of antimony is placed in the molten zone, which is passed through the pure germanium.

Integrated circuit

integrated circuitsmicrochipchip
This technique is also used for the preparation of silicon for use in computer chips.

Induction coil

Ruhmkorff coilinterruptercoil
Induction coils, ring-wound resistance heaters, or gas flames are common methods.

Electric heating

electric heaterElectricelectric heaters
Induction coils, ring-wound resistance heaters, or gas flames are common methods.