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Doping of a pure silicon array. Silicon based intrinsic semiconductor becomes extrinsic when impurities such as boron and antimony are introduced.. In semiconductor production, doping is the intentional introduction of impurities into an intrinsic (undoped) semiconductor for the purpose of modulating its electrical, optical and structural properties.
Phosphorus atom acting as a donor in the simplified 2D silicon lattice. For example, when silicon (Si), having four valence electrons, is to be doped as a n-type semiconductor, elements from group V like phosphorus (P) or arsenic (As) can be used because they have five valence electrons. A dopant with five valence electrons is also called a ...
A compound semiconductor is a semiconductor compound composed of chemical elements of at least two different species. These semiconductors form for example in periodic table groups 13–15 (old groups III–V), for example of elements from the Boron group (old group III, boron, aluminium, gallium, indium) and from group 15 (old group V, nitrogen, phosphorus, arsenic, antimony, bismuth).
The conductivity of silicon is increased by adding a small amount (of the order of 1 in 10 8) of pentavalent (antimony, phosphorus, or arsenic) or trivalent (boron, gallium, indium) atoms. [3] This process is known as doping, and the resulting semiconductors are known as doped or extrinsic semiconductors .
An extrinsic semiconductor is one that has been doped; during manufacture of the semiconductor crystal a trace element or chemical called a doping agent has been incorporated chemically into the crystal, for the purpose of giving it different electrical properties than the pure semiconductor crystal, which is called an intrinsic semiconductor.
They are distinct from arsenate silicates which have oxygen connected with arsenic and silicon, or arsenatosilicates with arsenate groups sharing oxygen with silicate. Arsenidosilicates have dark coloured crystals, usually metallic black. They are often decomposed by water, and some are unstable with respect to the water in air.
Crystalline silicon has a metallic luster and a grayish color. Single crystals can be grown with the Czochralski process. Crystalline silicon can be doped with elements such as boron, gallium, germanium, phosphorus or arsenic. Doped silicon is used in solid-state electronic devices, such as solar cells, rectifiers and computer chips. [1]
Silicon wafers are generally not 100% pure silicon, but are instead formed with an initial impurity doping concentration between 10 13 and 10 16 atoms per cm 3 of boron, phosphorus, arsenic, or antimony which is added to the melt and defines the wafer as either bulk n-type or p-type. [27]