翻訳と辞書 Words near each other ・ Quasar Khanh ・ Quasar Padamsee ・ Quasar, Quasar, Burning Bright ・ Quasar-Unipower ・ Quasars, Redshifts and Controversies ・ Quaschwitz ・ Quasdorf Blacksmith and Wagon Shop ・ Quashed ・ Quashnet River ・ Quashquame ・ Quasi ・ Quasi alliance ・ Quasi at the Quackadero ・ Quasi corporation ・ Quasi Delay Insensitive ・ Quasi Fermi level ・ Quasi in rem jurisdiction ・ Quasi Object ・ Quasi Self Boot 93–96 ・ Quasi Universal Intergalactic Denomination ・ Quasi-algebraically closed field ・ Quasi-analog signal ・ Quasi-analytic function ・ Quasi-arithmetic mean ・ Quasi-bialgebra ・ Quasi-biennial oscillation ・ Quasi-bipartite graph ・ Quasi-birth–death process ・ Quasi-category ・ Quasi-commutative property Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Quasi Fermi level ： ウィキペディア英語版 Quasi Fermi level A quasi Fermi level (also called imref, which is "fermi" spelled backwards) is a term used in quantum mechanics and especially in solid state physics for the Fermi level (chemical potential of electrons) that describes the population of electrons separately in the conduction band and valence band, when their populations are displaced from equilibrium. This displacement could be caused by the application of an external voltage, or by exposure to light of energy $E>E\_g$, which alter the populations of electrons in the conduction band and valence band. Since recombination rate (the rate of equilibration between bands) tends to be much slower than the energy relaxation rate within each band, the conduction band and valence band can each have an individual population that is internally in equilibrium, even though the bands are not in equilibrium with respect to exchange of electrons. The displacement from equilibrium is such that the carrier populations can no longer be described by a single Fermi level, however it is possible to describe using separate quasi-Fermi levels for each band. ==Definition== When a semiconductor is in thermal equilibrium, the distribution function of the electrons at the energy level of E is presented by Fermi–Dirac distribution function. In this case the Fermi level is defined as the level in which the probability of occupation of electron at that energy is 1/2. In thermal equilibrium, there is no need to distinguish between conduction band quasi-Fermi level and valence band quasi-Fermi level as they are simply equal to the Fermi level. When a disturbance from a thermal equilibrium situation occurs, the populations of the electrons in the conduction band and valence band change. If the disturbance is not too great or not changing too quickly, the bands each relax to a state of quasi thermal equilibrium. Because the relaxation time for electrons within the conduction band is much lower than across the band gap, we can consider that the electrons are in thermal equilibrium in the conduction band. This is also applicable for electrons in the valence band (often understood in terms of holes). We can define a quasi Fermi level and quasi temperature due to thermal equilibrium of electrons in conduction band, and quasi Fermi level and quasi temperature for the valence band similarly. We can state the general Fermi function for electrons in conduction band as $f\_c(k,r)\backslash approx\; f\_0(E,E\_,T\_c)$ and for electrons in valence band as $f\_v(k,r)\backslash approx\; f\_0(E,E\_,T\_v)$ where: *$f\_0(E,E\_F,T)=\backslash frac$ is the conduction band quasi-Fermi level at location ''r'', *$E\_$ is the valence band quasi-Fermi level at location ''r'', *$T\_c$ is the conduction band temperature, *$T\_v$ is the valence band temperature, *$f\_c(k,r)$ is the probability that a particular conduction-band state, with wavevector ''k'' and position ''r'', is occupied by an electron, *$f\_v(k,r)$ is the probability that a particular valence-band state, with wavevector ''k'' and position ''r'', is occupied by an electron (i.e. ''not'' occupied by a hole). *$E$ is the energy of the conduction- or valence-band state in question, *$k\_B$ is Boltzmann's constant. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Quasi Fermi level」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.