Electron Hole

Electron hole - Wikipedia, the free encyclopedia
The electron hole was introduced into calculations for the following two situations: If an electron is excited into a higher state it leaves a hole in its old state. ...
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electron hole: Definition from Answers.com
hole A gap left in the covalent bond when a valence electron gains sufficient energy to jump to the conduction ... If an electron is excited into higher state ...
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Carrier generation and recombination - Wikipedia, the free encyclopedia
(Redirected from Electron-hole pair) Jump to: navigation, search ... The electron-hole pair is the fundamental unit of generation and recombination, ...
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Electrons and ``holes'' : SOLID-STATE DEVICE THEORY
... energy can create few electron hole pairs resulting in weak conduction. ... The free electron and hole both contribute to conduction about the crystal lattice. ...
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SAMI2: Electron Hole Formation
The formation of the electron hole has a seasonal and longitudinal dependence. ... The electron hole does not form until after sunset (2000 LT) when the ionosphere ...
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Intrinsic Semiconductors
... flow in an intrinsic semiconductor consists of both electron and hole current. ... Effective masses of electrons and holes. Index. Semiconductor concepts ...
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An electron hole is the conceptual and mathematical opposite of an electron, useful in the study of physics and chemistry. The concept describes the lack of an electron. It is different from the positron, which is the antimatter duplicate of the electron.

The electron hole was introduced into calculations for the following two situations:

If an electron is excited into higher state it leaves a hole in its old state. This meaning is used in Auger electron spectroscopy (and other x-ray techniques), in computational chemistry, and to explain the low electron-electron scattering-rate in crystals (metals, semiconductors).
In crystals, band structure calculations lead to an effective mass for the charge carriers, which can be negative. Inspired by the Hall effect, Newton's law is used to attach the negative sign onto the charge.

Solid state physics

In solid state physics, an electron hole (usually referred to simply as a hole) is the absence of an electron from the otherwise full valence band. A full (or nearly full) valence band is present in semiconductors and Electrical insulations. The concept of a hole is essentially a simple way to analyze the electronic transitions within the valence band.

Hole conduction can be explained by the following analogy. Imagine a row of people seated in an auditorium, where there are no spare chairs. Someone in the middle of the row wants to leave, so he jumps over the back of the seat into an empty row, and walks out. The empty row is analogous to the conduction band, and the person walking out is analogous to a free electron.

Now imagine someone else comes along and wants to sit down. The empty row has a poor view; so he does not want to sit there. Instead, a person in the crowded row moves into the empty seat the first person left behind. The empty seat moves one spot closer to the edge and the person waiting to sit down. The next person follows, and the next, et cetera. One could say that the empty seat moves towards the edge of the row. Once the empty seat reaches the edge, the new person can sit down.

In the process everyone in the row has moved along. If those people were negatively charged (like electrons), this movement would constitute electrical conductivity. If the seats themselves were positively charged, then only the vacant seat would be positive. This is a very simple model of how hole conduction works.

In reality, due to the crystal structure properties, the hole is actually not localized to a single position as described in the previous example. Rather, the hole is delocalized and spans an area in the crystal lattice covering many hundreds of crystal structure. This is equivalent to the idea that we cannot tell which broken bond corresponds to the 'missing' electron, and is supported by uncertainty theorems from quantum mechanics.

Instead of analyzing the movement of an empty state in the valence band as the movement of billions of separate electrons, physicists propose a single imaginary particle called a "hole". In an applied electric field, all the electrons move one way, so the hole moves the other way. If a hole associates itself with a neutral atom, that atom loses an electron and becomes positive. The physicists therefore say that the hole must have positive electric charge—in fact, they assign a charge of +e, precisely the opposite of the electron charge.

Using Coulomb's law, we can calculate the force on the "hole" due to an electric field. Physicists then propose an effective mass which will relate the (imaginary) force on the (imaginary) hole to the acceleration of that hole. In some semiconductors, such as silicon, effective mass is dependent on direction (Anisotropy), however a value averaged over all directions can be used for some macroscopic calculations.

In most of the semiconductors, the effective mass of hole is larger than that of electron. This results in less mobility for holes under the influence of an electric field and this may slow down the speed of the electronic device made of that semiconductor. This is one major reason for adopting electrons as the primary charge carriers, whenever possible in semiconductor devices instead of holes.

Holes in quantum chemistry An alternate meaning for the term electron hole is used in computational chemistry. In coupled cluster methods, the ground (or lowest energy) state of a molecule is interpreted as the "vacuum state"—conceptually, in this state there are no electrons. In this scheme, the absence of an electron from a normally-filled state is called a "hole" and is treated as a particle, and the presence of an electron in a normally-empty state is simply called an "electron". This terminology is almost identical to that used in solid-state physics.

See also

Bandgap
Carrier generation and recombination
Effective mass
Electrical conduction
Semiconductor

Electron hole - Wikipedia, the free encyclopedia
An electron hole is the conceptual and mathematical opposite of an electron, useful in the study of physics and chemistry. The concept describes the lack of an electron.

Carrier generation and recombination - Wikipedia, the free ...
In the solid state physics of semiconductors, carrier generation and recombination are processes by which mobile electrons and electron holes are created and eliminated.

QMC projects
QMC projects ... THEORY OF THE ELECTRON-HOLE SYSTEM. A guess at the T=0 phase diagram of the electron-hole system

Electron-hole system revisited: A variational quantum Monte Carlo ...
Electron-hole system revisited: A variational quantum Monte Carlo study Xuejun Zhu Department of Physics &Astronomy, Rutgers University, Piscataway, New Jersey 08855 and Bell ...

University of Bath Online Publications Store - OPuS: A theory of ...
Title: A theory of electron-hole pair excitation in the adsorption of simple atoms on metal surfaces: Authors: Mizielinski, M: Issue Date: 6-May-2008

Electron Hole Pair
EHP is one man's journey into the unkown of electric music, using only a computer, Reason 3.0, Ableton live and an actual 80s Digital synth, along with an array of acoutstic ...

hole from FOLDOC
hole < electronics > The absence of an electron in a semiconductor material. In the electron model, a hole can be thought of as an incomplete outer electron shell in a doping ...

electron model from FOLDOC
Some language theorists consider language and the electron to be models in themselves. Contrast hole model. (1995-10-06) Try this search on Wikipedia, OneLook, Google

Electron-hole pair - What does EHP stand for? Acronyms and ...
Acronym Definition; EHP: Earthquake Hazards Program (US Geological Survey) EHP: Eastern Highlands Province (PNG) EHP: Educational Homestay Programs: EHP: Effective Horsepower

electron hole - definition of electron hole by the Free Online ...
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