# Tag Info

## New answers tagged electronic-band-theory

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The Fermi energy is the energy of the highest occupied state at absolute zero of a system of non-interacting (or mean-field interacting) fermions. So for a band structure, the Fermi energy is the energy of the highest-occupied level after you have filled al your bands with electrons. Note that each (spin) band can hold $N_{\textrm{cells}}$ electrons, where ...

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Metals are good conductors of electricity because the outer (valence) electrons of the metal atoms are only loosely bound to the nucleus and form molecular orbitals known as the conduction band. Electrons can move more or less freely through the conduction band and so metals conduct electricity generally well. When a metal is chemically oxidised its outer ...

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It's because valence electrons are bounded. For example, consider Si and SiO2. While Si is semiconductor, SiO2 is insulator because it has no free valence electrons. BTW, many metal oxides ARE NOT in fact insulators - for example ZnO, Fe3O4 are all conductors. But it's true that oxides of metals have lower conductivity than pure metals.

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I think the notion of ‘band structure’ is deeply related to a “quasi-particle view” of an interacting system – even, an strongly interacting one. This means that although the original elementary excitations of the system (e.g., single electrons in a metal) do not provide a good and efficient description of the states and energies of the interacting system ...

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If all the dopant electrons were removed from an n-doped material then the material would have a net positive charge. If an applied voltage removes some of the electrons from the material either new electrons will be attracted to the positive dopant ions from elsewhere in the circuit or, if there is not "rest of the circuit", you will have made a capacitor ...

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Density Functional Theory (DFT) is used to calculate the electronic structure and properties of metals as much and "successfully" as it is used for molecules, clusters, alloys, insulators and semiconductors. Of course there are certain things that DFT is good at and can and cannot do. However saying that "DFT calculations are not accurate for metallic ...

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DFT can theoretically depict the ground state of any material, however, we can only deal with the properties of material by using some approximation. the quality of your approximation determines the degree of accuracy.

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The dopant level is bound to the atom, and we can think of two different "ionization energies" that exist: one would be to freedom in the semiconductor's conduction band (call this $E_{d}$ - what we are interested in), and a larger one is the energy to complete freedom in the air (call this $E_{free}$). Electrons in the semiconductor can also be excited to ...

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The usual conduction mechanism for intrinsic semiconductors is that thermal excitation of electrons from the valence to conduction band creates mobile electrons in the conduction band and mobile holes in the valence band. Both of these move in response to an applied voltage and therefore conduct electricity. You're quite correct that if the band gap is ...

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