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Encyclopedia > Doping (semiconductors)

In semiconductor production, doping refers to the process of intentionally introducing impurities into an intrinsic semiconductor in order to change its electrical properties. The proper impurities are dependent upon the basic type of semiconductor used. A semiconductor is a material with an electrical conductance that is intermediate to those of an insulator and a conductor. ...


Some dopants are generally added as the (usually silicon) boule is grown, giving each wafer an almost uniform initial doping. To define circuit elements, selected areas (typically controlled by photolithography) are further doped by such processes as diffusion and ion implantation, the latter method being more popular in large production runs due to higher speed and greater overall control. General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... A boule is a term used to describe a single crystal ingot produced by synthetic means. ... See Wafer (cooking) for the original meaning of the word. ... Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a photomask (also called reticle) to the surface of a wafer or substrate. ... Diffusion is the spontaneous spreading of something such as particles, heat, or momentum. ... Ion implantation is a materials engineering process by which ions of a material can be implanted into another solid, thereby changing the physical properties of the solid. ...


The number of dopant atoms needed to create a difference in the ability of a semiconductor to conduct is very small. It will occur with the replacement of a semiconductor atom by only one in every 200 000 atoms.

Contents


Dopant elements

Group IV semiconductors

For the group IV semiconductors such as silicon, germanium, and silicon carbide, the most common dopants are group III or group V elements. (Group number refers to the Roman numerals of the columns in the Periodic Table of the Elements.) Arsenic, boron, gallium, phosphorus are all commonly used to dope silicon. General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... General Name, Symbol, Number germanium, Ge, 32 Series metalloids Group, Period, Block 14 (IVA), 4, p Density, Hardness 5323 kg/m3, 6 Appearance greyish white Atomic properties Atomic weight 72. ... Silicon carbide (SiC), also known as carborundum or moissanite, is a ceramic compound of silicon and carbon. ... The system of Roman numerals is a numeral system originating in ancient Rome, and was adapted from Etruscan numerals. ... The periodic table of the chemical elements, also called the Mendeleev periodic table, is a tabular display of the known chemical elements. ... General Name, Symbol, Number arsenic, As, 33 Chemical series metalloids Group, Period, Block 15, 4, p Appearance metallic gray Atomic mass 74. ... General Name, Symbol, Number Boron, B, 5 Series Metalloids Group, Period, Block 13 (IIIA), 2, p Density, Hardness 2460 kg/m3, 9. ... General Name, Symbol, Number gallium, Ga, 31 Chemical series poor metals Group, Period, Block 13, 4, p Appearance silvery white   Atomic mass 69. ... This article is about the chemical element. ...


By doping pure silicon with group V elements such as Phosphorus, extra valence electrons are added which become unbonded from individual atoms and allow the compound to be electrically conductive, n-type material. Doping with group III elements, such as Boron, which are missing the forth valence electron creates "broken bonds", or holes, in the silicon lattice that are free to move. This is electrically conductive, p-type material. In this context then, a group V element is said to behave as an electron donor, and a group III element as an acceptor. In chemistry, valence electrons are the electrons contained in the valence shell of an atom, and which are likely to participate in a chemical reaction through bonding with other atoms or molecules. ...


III-V and II-VI semiconductors

Other compound semiconductors such as gallium arsenide are quite often doped with group IV elements such as Si. In most cases, a low concentration of Si will preferrentially substitute for the group III element, and function as a donor. This article is about the chemical compound. ...

Compensation

In most cases, many types of impurity will be present. If an equal number of donors and acceptors are present in the semiconductor, the extra electrons provided by the former will be used to satisfy the broken bonds due to the other, so that doping produces no free carriers of either type. This phenomenon is known as compensation, and occurs at the p-n junction in the vast majority of semiconductor devices. Partial compensation, where donors outnumber acceptors or vice-versa, allows device makers to repeatedly reverse the type of a given portion of the material by applying successively higher doses of dopants. A p-n junction is formed by combining N-type and P-type semiconductors together in very close contact. ...


  Results from FactBites:
 
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By doping pure silicon with group V elements such as Phosphorus, tour de france speeds and doping extra valence electrons are added which become unbonded from individual atoms lance armstrong blood doping in sports doping and allow the compound to be electrically conductive, n-type material.
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Doping (semiconductor) - Wikipedia, the free encyclopedia (836 words)
By doping pure silicon with group V elements such as phosphorus, extra valence electrons are added which become unbonded from individual atoms and allow the compound to be electrically conductive, n-type material.
Doping with group III elements, such as boron, which are missing the fourth valence electron creates "broken bonds", or holes, in the silicon lattice that are free to move.
The second is electrochemical doping in which a polymer-coated, working electrode is suspended in an electrolyte solution in which the polymer is insoluble along with separate counter and reference electrodes.
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