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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 ...
The unpaired electrons in the dangling bonds of the surface atoms interact with each other to form an electronic state with a narrow energy band, located somewhere within the band gap of the bulk material. For simplicity, the surface state band is assumed to be half-filled with its Fermi level located at the mid-gap energy of the bulk.
An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb force resulting from their opposite charges. It is an electrically neutral quasiparticle regarded as an elementary excitation primarily in condensed matter, such as insulators, semiconductors, some metals, and in some liquids.
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.
The Downs–Thomson paradox (named after Anthony Downs and John Michael Thomson), also known as the Pigou–Knight–Downs paradox (after Arthur Cecil Pigou and Frank Knight), states that the equilibrium speed of car traffic on a road network is determined by the average door-to-door speed of equivalent journeys taken by public transport or the next best alternative.
Fluorescence microscopy relies upon fluorescent compounds, or fluorophores, in order to image biological systems.Since fluorescence and phosphorescence are competitive methods of relaxation, a fluorophore that undergoes intersystem crossing to the triplet excited state no longer fluoresces and instead remains in the triplet excited state, which has a relatively long lifetime, before ...
This is very similar to a true 'gap', which is an energy range that contains no allowed states. Such gaps open up, for example, when electrons interact with the lattice. The pseudogap phenomenon is observed in a region of the phase diagram generic to cuprate high-temperature superconductors, existing in underdoped specimens at temperatures ...