Gallium phosphide (
), a
phosphideIn chemistry, a phosphide is a compound of phosphorus with a less electronegative element or elements. Binary compounds are formed with the majority of less electronegative elements with the exception of Hg, Pb, Sb, Bi, Te, Po...
of
galliumGallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the Ga salt, in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies...
, is a
compoundA compound semiconductor is a semiconductor compound composed of elements from two or more different groups of the periodic table . For groups 13-15 ,...
semiconductor material with an indirect
band gapIn solid state physics, a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states exist...
of 2.26
eVIn physics, the electron volt is a unit of energy. By definition, it is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an electrostatic potential difference of one volt...
. Multi-crystalline material has the appearance of pale orange pieces. Undoped single crystal wafers appear clear orange, but strongly doped wafers appear darker due to free-carrier absorption. It is odorless and insoluble in water.
SulfurSulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant, multivalent non-metal. Sulfur, in its native form, is a yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals...
or
telluriumTellurium is a chemical element that has the symbol Te and atomic number 52. A brittle silver-white metalloid which looks similar to tin, tellurium is chemically related to selenium and sulfur. Tellurium is primarily used in alloys and as a semiconductor.-Characteristics:Tellurium is extremely...
are used as dopants to turn gallium phosphide into an
n-type semiconductorAn N-type semiconductor is a material obtained by carrying out a process of doping, that is, by adding some amount of an element with more electrons to a semiconductor element with fewer electrons, in order to increase the number of free charge carriers. In this case the charge carriers are...
.
ZincZinc , also known as spelter, is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
is used as a dopant for the
p-type semiconductorA P-type semiconductor is obtained by carrying out a process of doping, that is adding a certain type of atoms to the semiconductor in order to increase the number of free charge carriers ....
.
Gallium phosphide is also an optical material.
Gallium phosphide (
), a
phosphideIn chemistry, a phosphide is a compound of phosphorus with a less electronegative element or elements. Binary compounds are formed with the majority of less electronegative elements with the exception of Hg, Pb, Sb, Bi, Te, Po...
of
galliumGallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the Ga salt, in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies...
, is a
compoundA compound semiconductor is a semiconductor compound composed of elements from two or more different groups of the periodic table . For groups 13-15 ,...
semiconductor material with an indirect
band gapIn solid state physics, a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states exist...
of 2.26
eVIn physics, the electron volt is a unit of energy. By definition, it is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an electrostatic potential difference of one volt...
. Multi-crystalline material has the appearance of pale orange pieces. Undoped single crystal wafers appear clear orange, but strongly doped wafers appear darker due to free-carrier absorption. It is odorless and insoluble in water.
SulfurSulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant, multivalent non-metal. Sulfur, in its native form, is a yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals...
or
telluriumTellurium is a chemical element that has the symbol Te and atomic number 52. A brittle silver-white metalloid which looks similar to tin, tellurium is chemically related to selenium and sulfur. Tellurium is primarily used in alloys and as a semiconductor.-Characteristics:Tellurium is extremely...
are used as dopants to turn gallium phosphide into an
n-type semiconductorAn N-type semiconductor is a material obtained by carrying out a process of doping, that is, by adding some amount of an element with more electrons to a semiconductor element with fewer electrons, in order to increase the number of free charge carriers. In this case the charge carriers are...
.
ZincZinc , also known as spelter, is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
is used as a dopant for the
p-type semiconductorA P-type semiconductor is obtained by carrying out a process of doping, that is adding a certain type of atoms to the semiconductor in order to increase the number of free charge carriers ....
.
Gallium phosphide is also an optical material. Its
refractive indexThe refractive index of a medium is a measure of how much the speed of light is reduced inside the medium. For example, typical soda-lime glass has a refractive index close to 1.5, which means that in glass, light travels at 1 / 1.5 = 2/3 the speed of light in a vacuum...
is about 3.37 in the visible, but decreases to 3.2 at 800 nm (IR).
Light-emitting diodes
Gallium phosphide is used for manufacture of low and standard brightness red, orange, and green
light-emitting diodeA light-emitting diode , is an electronic light source. The first LED was built in the 1920s by Oleg Vladimirovich Losev, a radio technician who noticed that diodes used in radio receivers emitted light when current was passed through them...
s (LED). It is a low-cost material. GaP has been used as an LED material since the 1960s. It has a relatively short life at higher current and its lifetime is sensitive to temperature. It is used standalone or together with
gallium arsenide phosphideGallium arsenide phosphide is a semiconductor material, an alloy of gallium arsenide and gallium phosphide.Gallium arsenide phosphide is used for manufacturing red, orange and yellow light-emitting diodes. It is often grown on gallium phosphide substrate to form a GaP/GaAsP heterostructure...
.
Pure GaP LEDs emit green light at a wavelength of 555 nm.
NitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
-doped GaP emits at yellow-green (565 nm),
zinc oxideZinc oxide is an inorganic compound with the formula ZnO. It usually appears as a white powder, nearly insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber Zinc oxide is an inorganic compound with the...
doped GaP emits red (700 nm).
Gallium phosphide is transparent for yellow and red light, therefore GaAsP-on-GaP LEDs are more efficient than GaAsP-on-GaAs.
At temperatures above ~900 °C, gallium phosphide dissociates and the phosphorus escapes as a gas. To grow a crystal from a 1500 °C melt (for LED wafers), this must be prevented by holding the phosphorus in with a blanket of molten
boric oxideBoron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B2O3. It is almost always found as the vitreous form; however, it can be crystallized after extensive annealing...
in inert gas pressure of 10-100 atmospheres. The process is called Liquid Encapsulated Czochralski (LEC) growth, an elaboration of the
Czochralski processThe Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors , metals , salts, and synthetic gemstones...
used for silicon wafers.
Alloys
- Aluminium gallium indium phosphide
Aluminium gallium indium phosphide is a semiconductor material.AlGaInP is used in manufacture of light-emitting diodes of high-brightness red, orange, green, and yellow color, to form the heterostructure emitting light...
- Indium gallium phosphide
Indium gallium phosphide , also called gallium indium phosphide , is a semiconductor composed of indium, gallium and phosphorus...
- Gallium arsenide phosphide
Gallium arsenide phosphide is a semiconductor material, an alloy of gallium arsenide and gallium phosphide.Gallium arsenide phosphide is used for manufacturing red, orange and yellow light-emitting diodes. It is often grown on gallium phosphide substrate to form a GaP/GaAsP heterostructure...
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