Editing Fermi level (section)

===Nomenclature===

The term ''Fermi level'' is mainly used in discussing the solid state physics of electrons in [[semiconductor]]s, and a precise usage of this term is necessary to describe [[band diagram]]s in devices comprising different materials with different levels of doping.
In these contexts, however, one may also see Fermi level used imprecisely to refer to the ''band-referenced Fermi level'', ''μ''&nbsp;−&nbsp;''ϵ''<sub>C</sub>, called ''ζ'' above.
It is common to see scientists and engineers refer to "controlling", "[[Fermi level pinning|pinning]]", or "tuning" the Fermi level inside a conductor, when they are in fact describing changes in ''ϵ''<sub>C</sub> due to [[doping (semiconductor)|doping]] or the [[field effect (semiconductor)|field effect]].
In fact, [[thermodynamic equilibrium]] guarantees that the Fermi level in a conductor is ''always'' fixed to be exactly equal to the Fermi level of the electrodes; only the band structure (not the Fermi level) can be changed by doping or the field effect (see also [[band diagram]]).
A [[Electrochemical potential#Conflicting terminologies|similar ambiguity]] exists between the terms, ''[[chemical potential]]'' and ''[[electrochemical potential]]''.

It is also important to note that Fermi ''level'' is not necessarily the same thing as [[Fermi energy|Fermi ''energy'']].
In the wider context of quantum mechanics, the term [[Fermi energy]] usually refers to ''the maximum kinetic energy of a fermion in an idealized non-interacting, disorder free, zero temperature [[Fermi gas]]''.
This concept is very theoretical (there is no such thing as a non-interacting Fermi gas, and zero temperature is impossible to achieve). However, it finds some use in approximately describing [[white dwarf]]s, [[neutron star]]s, [[atomic nuclei]], and electrons in a [[metal]].
On the other hand, in the fields of semiconductor physics and engineering, ''Fermi energy'' often is used to refer to the Fermi level described in this article.<ref>For example: {{cite book|url=https://books.google.com/books?id=n0rf9_2ckeYC&pg=PA49 |title=Electronics (fundamentals And Applications)|author= D. Chattopadhyay|isbn=978-81-224-1780-7|year=2006|publisher=New Age International }} and {{cite book|url=https://books.google.com/books?id=lmg13dHPKg8C&pg=PA113| title=Semiconductor Physics and Applications|author=  Balkanski and Wallis|isbn=978-0-19-851740-5|date=2000-09-01| publisher=OUP Oxford}}</ref>