Quantum Well
A quantum well is a potential well with only discrete energy values. The classic model used to demonstrate a quantum well is to confine particles, which were initially free to move in three dimensions, to two dimensions, by forcing them to occupy a planar region. The effects of quantum confinement take place when the quantum well thickness becomes comparable to the de Broglie wavelength of the carriers (generally electrons and electron hole, holes), leading to energy levels called "energy subbands", i.e., the carriers can only have discrete energy values. The concept of quantum well was proposed in 1963 independently by Herbert Kroemer and by Zhores Alferov and R.F. Kazarinov.Zh. I. Alferov and R.F. Kazarinov, Authors Certificate 28448 (U.S.S.R) 1963. History The semiconductor quantum well was developed in 1970 by Leo Esaki, Esaki and Raphael Tsu, Tsu, who also invented synthetic superlattices. They suggested that a Heterojunction, heterostructure made up of alternating thin l ...
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Bandgap
In solid-state physics and solid-state chemistry, a band gap, also called a bandgap or energy gap, is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to the energy difference (often expressed in electronvolts) between the top of the valence band and the bottom of the conduction band in Electrical insulation, insulators and semiconductors. It is the energy required to promote an electron from the valence band to the conduction band. The resulting conduction-band electron (and the electron hole in the valence band) are free to move within the crystal lattice and serve as charge carriers to conduct electric current. It is closely related to the HOMO/LUMO, HOMO/LUMO gap in chemistry. If the valence band is completely full and the conduction band is completely empty, then electrons cannot move within the solid because there are no available states. If the electrons are not free to move within the ...
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Particle In A Box
In quantum mechanics, the particle in a box model (also known as the infinite potential well or the infinite square well) describes the movement of a free particle in a small space surrounded by impenetrable barriers. The model is mainly used as a hypothetical example to illustrate the differences between classical and quantum systems. In classical systems, for example, a particle trapped inside a large box can move at any speed within the box and it is no more likely to be found at one position than another. However, when the well becomes very narrow (on the scale of a few nanometers), quantum effects become important. The particle may only occupy certain positive energy levels. Likewise, it can never have zero energy, meaning that the particle can never "sit still". Additionally, it is more likely to be found at certain positions than at others, depending on its energy level. The particle may never be detected at certain positions, known as spatial nodes. The particle in ...
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Valence And Conduction Bands
In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level, and thus determine the electrical conductivity of the solid. In nonmetals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. On a graph of the electronic band structure of a semiconducting material, the valence band is located below the Fermi level, while the conduction band is located above it. The distinction between the valence and conduction bands is meaningless in metals, because conduction occurs in one or more partially filled bands that take on the properties of both the valence and conduction bands. Band gap In semiconductors and insulators the two bands are separated by a band gap, while in conductors the bands overlap. A band gap is an energy range in a solid where no electron states can exist due to th ...
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Stationary State
A stationary state is a quantum state with all observables independent of time. It is an eigenvector of the energy operator (instead of a quantum superposition of different energies). It is also called energy eigenvector, energy eigenstate, energy eigenfunction, or energy eigenket. It is very similar to the concept of atomic orbital and molecular orbital in chemistry, with some slight differences explained below. Introduction A stationary state is called ''stationary'' because the system remains in the same state as time elapses, in every observable way. For a single-particle Hamiltonian, this means that the particle has a constant probability distribution for its position, its velocity, its spin, etc. (This is true assuming the particle's environment is also static, i.e. the Hamiltonian is unchanging in time.) The wavefunction itself is not stationary: It continually changes its overall complex phase factor, so as to form a standing wave. The oscillation frequency of ...
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MCM QW1 GaAs
MCM may refer to: Measurements * Thousand circular mils or kcmil, the wire gauge is equivalent cross sectional area (500 MCM = 500,000 circular mils) * Million cubic metre, the unit of volume Music * Magic Circle Music, a heavy metal record label * Magic City Misfits, a roller derby team from Jacksonville, FL * Maverick City Music, a contemporary christian group * MCM (TV channel), a French music channel * Music City Mystique, a Percussion Independent World (PIW) Drumline * The Mad Capsule Markets, a Japanese punk-metal band * MCM – The Gospel: The Missing Gems of MCM Caveman (1994-2011) (Mark Layman), rapper and former frontman for UK hip-hop group Caveman * MCM Records, a French record label established by Jacques and Marcelle Morgantini Science * Medical countermeasure (MCM), products that can protect from the effects of a chemical, biological, or nuclear attack * Minichromosome maintenance protein, which forms DNA helicase in eukaryotic species * Mobil Composition ...
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Gallium Arsenide
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and optical windows. GaAs is often used as a substrate material for the epitaxial growth of other III-V semiconductors, including indium gallium arsenide, aluminum gallium arsenide and others. History Gallium arsenide was first synthesized and studied by Victor Goldschmidt in 1926 by passing arsenic vapors mixed with hydrogen over gallium(III) oxide at 600 °C. The semiconductor properties of GaAs and other Compound semiconductor, III-V compounds were patented by Heinrich Welker at Siemens-Schuckert in 1951 and described in a 1952 publication. Commercial production of its monocrystals commenced in 1954, and more studies followed in the 195 ...
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Aluminium Gallium Arsenide
Aluminium gallium arsenide (also gallium aluminium arsenide) ( Alx Ga1−x As) is a semiconductor material with very nearly the same lattice constant as GaAs, but a larger bandgap. The ''x'' in the formula above is a number between 0 and 1 - this indicates an arbitrary alloy between GaAs and AlAs. The chemical formula ''AlGaAs'' should be considered an abbreviated form of the above, rather than any particular ratio. The bandgap varies between 1.42 eV (GaAs) and 2.16 eV (AlAs). For x < 0.4, the bandgap is direct. The

MCM GaAs AlGaAs Structure
MCM may refer to: Measurements * Thousand circular mils or kcmil, the wire gauge is equivalent cross sectional area (500 MCM = 500,000 circular mils) * Million cubic metre, the unit of volume Music * Magic Circle Music, a heavy metal record label * Magic City Misfits, a roller derby team from Jacksonville, FL * Maverick City Music, a contemporary christian group * MCM (TV channel), a French music channel * Music City Mystique, a Percussion Independent World (PIW) Drumline * The Mad Capsule Markets, a Japanese punk-metal band * MCM – The Gospel: The Missing Gems of MCM Caveman (1994-2011) (Mark Layman), rapper and former frontman for UK hip-hop group Caveman * MCM Records, a French record label established by Jacques and Marcelle Morgantini Science * Medical countermeasure (MCM), products that can protect from the effects of a chemical, biological, or nuclear attack * Minichromosome maintenance protein, which forms DNA helicase in eukaryotic species * Mobil Composition ...
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Monolayer
A monolayer is a single, closely packed layer of entities, commonly atoms or molecules. Monolayers can also be made out of cells. ''Self-assembled monolayers'' form spontaneously on surfaces. Monolayers of layered crystals like graphene and molybdenum disulfide are generally called '' 2D materials''. Types A Langmuir monolayer or ''insoluble monolayer'' is a one-molecule thick layer of an insoluble organic material spread onto an aqueous subphase in a Langmuir–Blodgett trough. Traditional compounds used to prepare Langmuir monolayers are amphiphilic materials that possess a hydrophilic headgroup and a hydrophobic tail. Since the 1980s a large number of other materials have been employed to produce Langmuir monolayers, some of which are semi-amphiphilic, including polymeric, ceramic or metallic nanoparticles and macromolecules such as polymers. Langmuir monolayers are extensively studied for the fabrication of Langmuir–Blodgett film (LB films), which are formed by transf ...
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Chemical Vapor Deposition
Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (electronics), wafer (substrate) is exposed to one or more Volatility (chemistry), volatile wikt:precursor, precursors, which chemical reaction, react and/or chemical decomposition, decompose on the substrate surface to produce the desired deposit. Frequently, volatile by-products are also produced, which are removed by gas flow through the reaction chamber. Microfabrication processes widely use CVD to deposit materials in various forms, including: Single crystal, monocrystalline, polycrystalline, amorphous, and Epitaxy, epitaxial. These materials include: silicon (Silicon dioxide, dioxide, silicon carbide, carbide, silicon nitride, nitride, silicon oxynitride, oxynitride), carbon (carbon (fiber), fiber, carbon nanofibers, nanofibers, carbon nanot ...
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Molecular Beam Epitaxy
Molecular-beam epitaxy (MBE) is an epitaxy method for thin-film deposition of single crystals. MBE is widely used in the manufacture of semiconductor devices, including transistors. MBE is used to make diodes and MOSFETs (MOS field-effect transistors) at microwave frequencies, and to manufacture the lasers used to read optical discs (such as CDs and DVDs). History The original ideas of the MBE process were first established by K. G. Günther. Films that he deposited were not epitaxial, but were deposited on glass substrates. With the development of vacuum technology, the MBE process was demonstrated by John Davey and Titus Pankey who succeeded in growing GaAs epitaxial films on single crystal GaAs substrates using Günther's method. Major subsequent development of MBE films was enabled by J.R. Arthur's investigations of kinetic behavior of growth mechanisms and Alfred Y. Cho's in situ observation of MBE process using reflection high-energy electron diffraction (RHEED) in the ...
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