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Band diagram for Schottky barrier at equilibrium Band diagram for semiconductor heterojunction at equilibrium. In solid-state physics of semiconductors, a band diagram is a diagram plotting various key electron energy levels (Fermi level and nearby energy band edges) as a function of some spatial dimension, which is often denoted x. [1]
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.
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.
µ is the total chemical potential of electrons, or Fermi level (in semiconductor physics, this quantity is more often denoted E F). The Fermi level of a solid is directly related to the voltage on that solid, as measured with a voltmeter. Conventionally, in band structure plots the Fermi level is taken to be the zero of energy (an arbitrary ...
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 ...
The vertical size of the barrier in the energy diagram corresponds to the built-in potential V bi. In the spatial axis the equilibration of Fermi levels produces a space charge region or depletion region of size w. A positive voltage applied to the back contact in (b) raises the Fermi level of electrons E Fn, and decreases the size of the ...
is the w:conduction band, indicates the quasi-w:fermi energy levels, is the intrinsic Fermi level of the undoped semiconductor, and is the w:valence band. This band alignment is due to the biasing conditions that correspond with forward-active mode; forward bias on the emitter-base junction and reverse bias on the base-collector junction.
Energy band diagram of a simple NPN w: ... fermi energy level, is the intrinsic Fermi level of the undoped semiconductor, and is the w:valence band ...