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In solid state physics and related applied fields, the band gap, also called an energy gap or stop band, is a region where a particle or quasiparticle is forbidden from propagating. Solid-state physics, the largest branch of Condensed matter physics, is the study of rigid Matter, or Solids The bulk of solid-state physics theory and In Physics, a quasiparticle refers to a particle -like entity arising in certain systems of interacting particles For insulators and semiconductors, the band gap generally refers to the energy difference between the top of the valence band and the bottom of the conduction band. An insulator, also called a Dielectric, is a material that resists the flow of Electric current. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that In Solids the valence band is the highest range of Electron energies where electrons are normally present at Absolute zero. In the Physics field of Semiconductors and insulators the conduction band is the range of Electron Energy, higher than that of the

Contents

In semiconductor physics

Semiconductor band structure.
Semiconductor band structure. In Solid-state physics, the electronic band structure (or simply band structure) of a Solid describes ranges of Energy that an Electron

In semiconductors and insulators, electrons are confined to a number of bands of energy, and forbidden from other regions. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Solid-state physics, the electronic band structure (or simply band structure) of a Solid describes ranges of Energy that an Electron The term "band gap" refers to the energy difference between the top of the valence band and the bottom of the conduction band; electrons are able to jump from one band to another. In Solids the valence band is the highest range of Electron energies where electrons are normally present at Absolute zero. In the Physics field of Semiconductors and insulators the conduction band is the range of Electron Energy, higher than that of the

The conductivity of intrinsic semiconductors is strongly dependent on the band gap. Electrical conductivity or specific conductivity is a measure of a material's ability to conduct an Electric current. An intrinsic semiconductor, also called an undoped semiconductor or i-type semiconductor, is a pure Semiconductor without any significant Dopant The only available carriers for conduction are the electrons which have enough thermal energy to be excited across the band gap.

Band gap engineering is the process of controlling or altering the band gap of a material by controlling the composition of certain semiconductor alloys, such as GaAlAs, InGaAs, and InAlAs. An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has It is also possible to construct layered materials with alternating compositions by techniques like molecular beam epitaxy. Molecular beam Epitaxy (MBE, is one of several methods of depositing Single crystals It was invented in the late 1960s at Bell Telephone Laboratories These methods are exploited in the design of heterojunction bipolar transistors (HBTs), laser diodes and solar cells. The Heterojunction bipolar transistor ( HBT) is an improvement of the Bipolar junction transistor (BJT that can handle signals of very high frequencies A laser diode is a Laser where the active medium is a Semiconductor similar to that found in a Light-emitting diode. A solar cell or photovoltaic cell is a device that converts Solar energy into Electricity by the photovoltaic effect.

The distinction between semiconductors and insulators is a matter of convention. One approach is to think of semiconductors as a type of insulator with a low band gap. Insulators with a higher band gap, usually greater than 3 eV, are not considered semiconductors and generally do not exhibit semiconductive behaviour under practical conditions. Electron mobility also plays a role in determining a material's informal classification. In Physics, electron mobility (or simply mobility) is a quantity relating the Drift velocity of Electrons to the applied Electric field

Band gaps depend on temperature because of thermal expansion. Thermal Expansion is the tendency of matter to change in Volume in response to a change in temperature Band gaps also depend on pressure. Band gaps can be either direct or indirect bandgaps, depending on the band structure. In Semiconductor Physics, a direct Bandgap means that the minimum energy of the Conduction band lies directly above the maximum energy of the In Semiconductor Physics, an indirect bandgap is a Bandgap in which the minimum energy in the Conduction band is shifted by a In Solid-state physics, the electronic band structure (or simply band structure) of a Solid describes ranges of Energy that an Electron

Mathematical interpretation

Classically, the ratio of probabilities that two states with an energy difference ΔE will be occupied by an electron is given by the Boltzmann factor:

e^{\left(\frac{-\Delta E}{kT}\right)}

where:

e is the exponential function
\, \Delta E is the energy difference
\, k is Boltzmann's constant
\, T is temperature

At the Fermi level (or chemical potential), the probability of a state being occupied is ½. In Physics, the Boltzmann factor is a weighting factor that determines the relative probability of a state i in a multi-state system in Thermodynamic equilibrium The exponential function is a function in Mathematics. The application of this function to a value x is written as exp( x) Bridge from macroscopic to microscopic physics Boltzmann's constant k is a bridge between Macroscopic and microscopic physics Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The Fermi energy is a concept in Quantum mechanics usually referring to the energy of the highest occupied Quantum state in a system of Fermions at In Thermodynamics and Chemistry, chemical potential, symbolized by μ, is a term introduced by the American engineer chemist and mathematical If the Fermi level is in the middle of a band gap of 1 eV, this ratio is e -20 or about 2. 0•10-9 at the room-temperature thermal energy of 25. 9 meV.

List of band gaps

Material Symbol Band gap (eV) @ 300K
Silicon Si 1. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 11 [1]
Germanium Ge 0. Germanium (dʒɚˈmeɪniəm is a Chemical element with the symbol Ge and Atomic number 32 67 [1]
Silicon carbide SiC 2. Silicon carbide ( is a compound of Silicon and Carbon bonded together to form Ceramics but it also occurs in nature as the extremely rare mineral 86 [1]
Aluminum phosphide AlP 2. Aluminium phosphide is the Chemical compound with the formula AlP 45 [1]
Aluminium arsenide AlAs 2. Aluminium arsenide (also aluminum arsenide) AlAs, is a Semiconductor material with almost the same Lattice constant as GaAs and 16 [1]
Aluminium antimonide AlSb 1. Aluminium antimonide (AlSb is a Semiconductor material of the III-V family containing Aluminium and Antimony. 6 [1]
Aluminium nitride AlN 6. Aluminium nitride ( Al[[Nitrogen N]] is a Nitride of Aluminium. 3
Diamond C 5. In Mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in 5
Gallium(III) phosphide GaP 2. Gallium phosphide () a Phosphide of Gallium, is a compound Semiconductor material with an indirect Band gap 26 [1]
Gallium(III) arsenide GaAs 1. Gallium arsenide ( GaAs) is a compound of two elements Gallium and Arsenic. 43 [1]
Gallium(III) nitride GaN 3. Gallium nitride ( is a very hard material commonly used in bright LEDs since the 1990s 4 [1]
Gallium(II) sulfide GaS 2. Gallium(II sulfide, GaS is a Chemical compound of Gallium and Sulfur. 5 (@ 295 K)
Gallium antimonide GaSb 0. Gallium antimonide (GaSb is a semiconducting compound of Gallium and Antimony of the III-V family 7 [1]
Indium(III) phosphide InP 1. Indium phosphide ( is a binary Semiconductor composed of Indium and Phosphorus. 35 [1]
Indium(III) arsenide InAs 0. Indium arsenide, InAs, or indium monoarsenide, is a Semiconductor material, a Semiconductor composed of Indium and Arsenic 36 [1]
Zinc sulfide ZnS 3. Zinc sulfide (or zinc sulphide is a Chemical compound with the formula Zn[[Sulfur S]] 6 [1]
Zinc selenide ZnSe 2. Zinc selenide ( Zn[[Selenium Se]] is a light yellow binary solid compound 7 [1]
Zinc telluride ZnTe 2. Zinc telluride is the Chemical compound with the formula ZnTe 25 [1]
Cadmium sulfide CdS 2. Cadmium sulfide is a chemical compound with the formula CdS. Cadmium sulfide is yellow in colour and is a semiconductor 42 [1]
Cadmium selenide CdSe 1. Cadmium selenide ( Cd[[Selenium Se]] is a solid binary compound of cadmium and selenium 73 [1]
Cadmium telluride CdTe 1. Cadmium telluride (CdTe is a Crystalline compound formed from Cadmium and Tellurium with a zinc blende (cubic crystal structure 49 [2]
Lead(II) sulfide PbS 0. Lead(II sulfide (also spelled sulphide, see Sulfur#Spelling) is a Chemical compound, most often purified from the Mineral Galena 37 [1]
Lead(II) selenide PbSe 0. Lead selenide () or lead(II selenide, a Selenide of Lead, is a Semiconductor material. 27 [1]
Lead(II) telluride PbTe 0. Lead telluride is a compound of lead and Tellurium (PbTe it is a Narrow gap semiconductor. 29 [1]

In photonics and phononics

In photonics band gaps or stop bands are ranges of photon frequencies where, if tunneling effects are neglected, no photons can be transmitted through a material. Photonics is the science of generating controlling and detecting Photons particularly in the visible and near Infra-red spectrum, but A material exhibiting this behaviour is known as a photonic crystal. Photonic crystals are periodic Optical (nanostructures that are designed to affect the motion of Photons in a similar way that periodicity of a Semiconductor

Similar physics applies to phonons in a phononic crystal. In Physics, a phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the Atomic lattice of a Solid A phononic crystal is a material which exhibits Stop bands for Phonons preventing phonons of selected ranges of frequencies from being transmitted through the material

References

  1. ^ a b c d e f g h i j k l m n o p q r s t Streetman, Ben G. ; Sanjay Banerjee (2000). Solid State electronic Devices, 5th edition, New Jersey: Prentice Hall, 524. New Jersey ( is a state in the Mid-Atlantic and Northeastern regions of the United States. Prentice Hall is a leading educational publisher It is an Imprint of Pearson Education Inc ISBN 0-13-025538-6.  
  2. ^ Madelung, Otfried (1996). Semiconductors - Basic Data, 2nd rev. ed. , Berlin Heidelberg New York: Springer-Verlag. Springer Science+Business Media or Springer (ˈʃpʁɪŋɐ is a worldwide Publishing company based in Germany, which publishes textbooks academic ISBN 3-540-60883-4.  

See also

Chemicals

List of electronics topics

References

External links

Aluminium gallium arsenide (also aluminum gallium arsenide) ( Al x Ga 1-x As) is a Semiconductor material with very Boron nitride ( BN) is a binary chemical compound, consisting of equal numbers of Boron and Nitrogen atoms Indium gallium arsenide ( InGaAs) is a Semiconductor composed of Indium, Gallium and Arsenic. Gallium arsenide ( GaAs) is a compound of two elements Gallium and Arsenic. Germanium (dʒɚˈmeɪniəm is a Chemical element with the symbol Ge and Atomic number 32 Metallic hydrogen results when Hydrogen is sufficiently Compressed and undergoes a phase change it is an example of Degenerate matter. Alphabetization has been neglected in some parts of this article (the "b" section in particular Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical A bandgap voltage reference is a Voltage reference circuit widely used in Integrated circuits usually with an output voltage around 1 Condensed matter physics is the field of Physics that deals with the macroscopic physical properties of Matter. In Semiconductor Physics, a direct Bandgap means that the minimum energy of the Conduction band lies directly above the maximum energy of the Electrical conduction is the movement of electrically charged particles through a Transmission medium ( Electrical conductor) An electron hole is the conceptual and mathematical Opposite of an Electron, useful in the study of Physics and Chemistry. The field-effect transistor (FET is a type of Transistor that relies on an Electric field to control the shape and hence the conductivity of a 'channel' In Semiconductor Physics, an indirect bandgap is a Bandgap in which the minimum energy in the Conduction band is shifted by a A photodiode is a type of Photodetector capable of converting Light into either current or Voltage, depending upon the mode of operation A photoresistor or Light Dependent Resistor or CdS Cell is a Resistor whose resistance decreases with increasing incident light intensity Photovoltaics ( PV) is the field of technology and research related to the application of Solar cells for Energy by converting Sunlight directly A solar cell or photovoltaic cell is a device that converts Solar energy into Electricity by the photovoltaic effect. Solid-state physics, the largest branch of Condensed matter physics, is the study of rigid Matter, or Solids The bulk of solid-state physics theory and A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that Semiconductor devices are Electronic components that exploit the electronic properties of Semiconductor materials principally Silicon, Germanium Strongly correlated materials are a wide class of materials that show unusual (often technologically useful electronic and Magnetic properties such as metal-insulator In Solids the valence band is the highest range of Electron energies where electrons are normally present at Absolute zero.
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