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  2. Fermi level - Wikipedia

    en.wikipedia.org/wiki/Fermi_level

    The Fermi level does not necessarily correspond to an actual energy level (in an insulator the Fermi level lies in the band gap), nor does it require the existence of a band structure. Nonetheless, the Fermi level is a precisely defined thermodynamic quantity, and differences in Fermi level can be measured simply with a voltmeter.

  3. Electronic band structure - Wikipedia

    en.wikipedia.org/wiki/Electronic_band_structure

    The most important bands and band gaps—those relevant for electronics and optoelectronics—are those with energies near the Fermi level. The bands and band gaps near the Fermi level are given special names, depending on the material: In a semiconductor or band insulator, the Fermi level is surrounded by a band gap, referred to as the band ...

  4. Fermi surface - Wikipedia

    en.wikipedia.org/wiki/Fermi_surface

    A material whose Fermi level falls in a gap between bands is an insulator or semiconductor depending on the size of the bandgap. When a material's Fermi level falls in a bandgap, there is no Fermi surface.

  5. Topological insulator - Wikipedia

    en.wikipedia.org/wiki/Topological_insulator

    The Fermi level falls within the bulk band gap which is traversed by topologically-protected spin-textured Dirac surface states. [ 1 ] [ 2 ] A topological insulator is a material whose interior behaves as an electrical insulator while its surface behaves as an electrical conductor , [ 3 ] meaning that electrons can only move along the surface ...

  6. Band diagram - Wikipedia

    en.wikipedia.org/wiki/Band_diagram

    Out of equilibrium (e.g., when voltage differences are applied), the Fermi level will not be flat. Furthermore, in semiconductors out of equilibrium it may be necessary to indicate multiple quasi-Fermi levels for different energy bands, whereas in an out-of-equilibrium insulator or vacuum it may not be possible to give a quasi-equilibrium ...

  7. Electrical resistivity and conductivity - Wikipedia

    en.wikipedia.org/wiki/Electrical_resistivity_and...

    An important part of band theory is that there may be forbidden bands of energy: energy intervals that contain no energy levels. In insulators and semiconductors, the number of electrons is just the right amount to fill a certain integer number of low energy bands, exactly to the boundary. In this case, the Fermi level falls within a band gap.

  8. Valence and conduction bands - Wikipedia

    en.wikipedia.org/wiki/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.

  9. Template:Band structure filling diagram - Wikipedia

    en.wikipedia.org/wiki/Template:Band_structure...

    The shade follows the Fermi–Dirac distribution (black: all states filled, white: no state filled). In metals and semimetals the Fermi level E F lies inside at least one band. In insulators and semiconductors the Fermi level is inside a band gap ; however, in semiconductors the bands are near enough to the Fermi level to be thermally populated ...