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- The band gap is the energy difference between the lowest conduction band and the highest valence band in a semiconductor. The distance between the conduction band and the valence band of electrons is known as a band gap.
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Nov 17, 2023 · The band gap is the energy difference between the lowest conduction band and the highest valence band in a semiconductor. The distance between the conduction band and the valence band of electrons is known as a band gap. The minimal energy needed to excite an electron up to a condition in the conduction band where it can engage in conduction is ...
The band gap is a very important property of a semiconductor because it determines its color and conductivity. Many of the applications of semiconductors are related to band gaps: Narrow gap materials (Hg x Cd 1 - x Te, VO 2 , InSb, Bi 2 Te 3 ) are used as infrared photodetectors and thermoelectrics (which convert heat to electricity).
- The Band Gap Energy
- Semiconductors with Direct Or Indirect Band Gap
- Importance of The Band Gap Energy For Photonic Devices
- Band Gap Engineering
- Quantum Wells and Quantum Dots
- Effect of Impurities and Crystal Defects
- Photonic Band Gaps
- More to Learn
In the case of dielectrics (insulators) and semiconductors, the band gap energyis understood to be the width of the energy gap between the conduction and valence band. For metals, one would have to ask which band gap is meant. For single-photon processes, the optical wavelength corresponding to a given band gap energy Egcan be calculated as or nume...
Direct Band Gap
A direct band gap is defined as one where the k vector (not only its magnitude, but also its direction) is about the same for the highest states in the valence band as for the lowest states in the conduction band. (The k vector is associated with the position within the Brillouin zone.) This is relevant for optical transitions. These involve only a minor change of the magnitude of the k vector because the optical wavelength is much longer than the interatomic distances or the lattice period....
Indirect Band Gap
In the case of an indirect band gap, the k vector of the lowest states in the conduction band substantially differs from that for the highest states in the valence band. As a consequence, absorption processes with photon energies only slightly above the band gap energy are hindered by the fact that there are no target states in the conduction band which have a suitable energy in addition to a suitable k vector. In other words, one cannot simultaneously fulfill energy conservation and momentum...
The band gap energy is important for various kinds of photonic devices. Some examples: 1. The emission wavelengths of light emitting diodes and laser diodesare largely determined by the band gap energy. The higher that energy, the shorter the wavelengths. Note that the strongest emission occurs at photon energy is slightly above the band gap energy...
Ternary and quaternary semiconductor compounds usually have a composition parameter, which influences the band gap properties, in particular the band gap energy. For example, one often uses indium gallium arsenide = InGaAs, more precisely InxGa1-xAs. The composition parameter x indicates the fraction of indium which is added to replace gallium. The...
So far, we have considered only homogeneous materials. If a material is inhomogeneous, for example containing quantum well or quantum dot structures, the electronic properties around those structures are modified. Frequently, one has a locally reduced band gap energy, so that quantum wells or dots in a medium can be absorbing even if the surroundin...
The above considerations all applied to intrinsic materials. Additional electronic states can be provided by impurities (often intentionally introduced as dopants) and crystal defects (which may also be intentionally increased, e.g. with low-temperature growth). Grain boundaries in polycrystalline materials can also be considered as crystal defects...
In certain situations, so-called photonic band gaps arise; here, one considers states of the light field rather than states of electrons. Just as an electron cannot be described with a plane de Broglie wave in a medium with a periodically varying electric potential, optical plane waves are no solutions of the wave equation in a medium with a period...
Encyclopedia articles: 1. absorption 2. fluorescence 3. laser diodes 4. photodiodes 5. dielectric materials
In solid-state physics, this energy gap or band gap is an energy range between valence band and conduction band where electron states are forbidden. Properties of semiconductors are determined by the energy gap between valence and conduction bands.
The main points about band gaps: The band gap is the minimum amount of energy required for an electron to break free from its bound state and become conductive (flow freely in the material). When an electron becomes conductive, a hole is left behind.
In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference (in electron volts) between the top of the valence band and the bottom of the conduction band in insulators and semiconductors.
- Matmatch. What is Band Gap? A band gap is a range of energy levels in a material in which electrons cannot exist. The absence or presence of a band gap as well as its size can help us understand the electronic behaviour of a material a.nd distinguish electrical insulators, conductors, and semiconductors [1]. In this article you will learn about:
