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Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, ... it has the same number of valence electrons as valence orbitals: ...
Charge carrier density, also known as carrier concentration, denotes the number of charge carriers per volume. In SI units, it is measured in m −3. As with any density, in principle it can depend on position. However, usually carrier concentration is given as a single number, and represents the average carrier density over the whole material.
Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below.
The maximum number of electrons that can be placed in a subshell is given by 2(2 l + 1). This gives two electrons in an s subshell, six electrons in a p subshell, ten electrons in a d subshell and fourteen electrons in an f subshell.
For example, the pure semiconductor silicon has four valence electrons that bond each silicon atom to its neighbors. [34] In silicon, the most common dopants are group III and group V elements. Group III elements all contain three valence electrons, causing them to function as acceptors when used to dope silicon.
The tendency to lose electrons increases as the size of the atom increases, as it does with increasing atomic number. Carbon alone forms negative ions , in the form of carbide (C 4− ) ions. Silicon and germanium , both metalloids , each can form +4 ions.
The SI unit of velocity is m/s, and the SI unit of electric field is V/m. Therefore the SI unit of mobility is (m/s)/(V/m) = m 2 /(V⋅s). However, mobility is much more commonly expressed in cm 2 /(V⋅s) = 10 −4 m 2 /(V⋅s). Mobility is usually a strong function of material impurities and temperature, and is determined empirically.
Silicon-29 is of note as the only stable silicon isotope with a nuclear spin (I = 1/2). [13] As such, it can be employed in nuclear magnetic resonance and hyperfine transition studies, for example to study the properties of the so-called A-center defect in pure silicon.