Energy range in a solid where no electron states exist
This article is about solid state physics. For voltage control circuitry in electronics, see Bandgap voltage reference.
This article is about the electronic bandgap found in semiconductors. For the photonic band gap, see Photonic crystal.
Graph of carbon atoms being brought together to form a diamond crystal, demonstrating formation of the electronic band structure and band gap. The right graph shows the energy levels as a function of the spacing between atoms. When far apart (right side of graph) all the atoms have discrete valence orbitals p and s with the same energies. However, when the atoms come closer (left side), their electron orbitals begin to spatially overlap and hybridize into N molecular orbitals each with a different energy, where N is the number of atoms in the crystal. Since N is such a large number, adjacent orbitals are extremely close together in energy so the orbitals can be considered a continuous energy band. At the actual diamond crystal cell size (denoted by a), two bands are formed, called the valence and conduction bands, separated by a 5.5 eV band gap. The Pauli exclusion principle limits the number of electrons in a single orbital to two, and the bands are filled beginning with the lowest energy.
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 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 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 crystal lattice, then there is no generated current due to no net charge carrier mobility. However, if some electrons transfer from the valence band (mostly full) to the conduction band (mostly empty), then current can flow (see carrier generation and recombination). Therefore, the band gap is a major factor determining the electrical conductivity of a solid. Substances having large band gaps (also called "wide" band gaps) are generally insulators, those with small band gaps (also called "narrow" band gaps) are semiconductor, and conductors either have very small band gaps or none, because the valence and conduction bands overlap to form a continuous band.
a bandgap, 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...
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the bandgap of a semiconductor can be of two basic types, a direct bandgap or an indirect bandgap. The minimal-energy state in the conduction band and...
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conduction bands. In semiconductors and insulators the two bands are separated by a bandgap, while in conductors the bands overlap. A bandgap is an energy...
energy that they may not have (called bandgaps or forbidden bands). Band theory derives these bands and bandgaps by examining the allowed quantum mechanical...
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In solid-state physics, an energy gap or bandgap is an energy range in a solid where no electron states exist, i.e. an energy range where the density...
bandgap, inducing partially filled states in both the band of states beneath the bandgap (valence band) and the band of states above the bandgap (conduction...
semiconductors the filled valence band is separated from an empty conduction band by a bandgap. For insulators, the magnitude of the bandgap is larger (e.g., > 4 eV)...
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Semiconductor materials are nominally small bandgap insulators. The defining property of a semiconductor material is that it can be compromised by doping...
opening up the complete photonic bandgap. The first one is to increase the refractive index contrast for the bandgap in each direction becomes wider...
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constant voltage corresponding to the particular semiconductor's theoretical bandgap, with very little fluctuations from variations of power supply, electrical...
ZnO has a relatively wide direct bandgap of ~3.3 eV at room temperature. Advantages associated with a wide bandgap include higher breakdown voltages...
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With a tunable bandgap, specific electronic components could be made-to-order for applications that require specific bandgaps. The bandgap can be brought...
heterostructure made up of alternating thin layers of semiconductors with different band-gaps should exhibit interesting and useful properties. Since then, much effort...
semiconductor with a bandgap of around 0.3 eV or 0.4 eV. It can also be prepared in a semiconducting amorphous form, with a bandgap of around 1.2–1.4 eV...
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