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In solid-state physics, metal-induced gap states are electron states that exist near the surface of a semiconductor due to the presence of a metal on the surface. They have energies that fall within the semiconductor's bandgap thus are forbidden in the bulk of the semiconductor.
The nature of these metal-induced gap states and their occupation by electrons tends to pin the center of the band gap to the Fermi level, an effect known as Fermi level pinning. Thus the heights of the Schottky barriers in metal–semiconductor contacts often show little dependence on the value of the semiconductor or metal work functions, in ...
Shown is the graphical definition of the Schottky barrier height, Φ B, for an n-type semiconductor as the difference between the interfacial conduction band edge E C and Fermi level E F. Whether a given metal-semiconductor junction is an ohmic contact or a Schottky barrier depends on the Schottky barrier height, Φ B, of the junction.
As an example the band bending induced by the forming of a p-n junction or a metal-semiconductor junction can be modified by applying a bias voltage . This voltage adds to the built-in potential ( V B I {\displaystyle V_{BI}} ) that exists in the depletion region ( V B I − V A {\displaystyle V_{BI}-V_{A}} ). [ 6 ]
This model includes a dipole layer at the interface between the two semiconductors which arises from electron tunneling from the conduction band of one material into the gap of the other (analogous to metal-induced gap states). This model agrees well with systems where both materials are closely lattice matched [11] such as GaAs/AlGaAs.
If there is a state at the Fermi level (ϵ = μ), then this state will have a 50% chance of being occupied. The distribution is plotted in the left figure. The closer f is to 1, the higher chance this state is occupied. The closer f is to 0, the higher chance this state is empty.
An ohmic contact is a non-rectifying electrical junction: a junction between two conductors that has a linear current–voltage (I–V) curve as with Ohm's law.Low-resistance ohmic contacts are used to allow charge to flow easily in both directions between the two conductors, without blocking due to rectification or excess power dissipation due to voltage thresholds.
In theoretical chemistry, Marcus theory is a theory originally developed by Rudolph A. Marcus, starting in 1956, to explain the rates of electron transfer reactions – the rate at which an electron can move or jump from one chemical species (called the electron donor) to another (called the electron acceptor). [1]