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It is somewhat crude to suggest that the metal-induced gap states (MIGS) are tail ends of metal states that leak into the semiconductor.Since the mid-gap states do exist within some depth of the semiconductor, they must be a mixture (a Fourier series) of valence and conduction band states from the bulk.
It was noted in 1947 by John Bardeen that the Fermi level pinning phenomenon would naturally arise if there were chargeable states in the semiconductor right at the interface, with energies inside the semiconductor's gap. These would either be induced during the direct chemical bonding of the metal and semiconductor (metal-induced gap states ...
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 ...
Since then, these materials as well as others exhibiting a transition between a metal and an insulator have been extensively studied, e.g. by Sir Nevill Mott, after whom the insulating state is named Mott insulator. The first metal-insulator transition to be found was the Verwey transition of magnetite in the 1940s. [3]
(Ni 2+ O 2−) 2 → Ni 3+ O 2− + Ni 1+ O 2−. In this situation, the formation of an energy gap preventing conduction can be understood as the competition between the Coulomb potential U between 3 d electrons and the transfer integral t of 3 d electrons between neighboring atoms (the transfer integral is a part of the tight binding ...
For binuclear reductive elimination, the oxidation state of each metal decreases by one, while the d-electron count of each metal increases by one. This type of reactivity is generally seen with first row metals, which prefer a one-unit change in oxidation state, but has been observed in both second and third row metals.
A pseudogap can be seen with several different experimental methods. One of the first observations was in NMR measurements of YBa 2 Cu 3 O 6+x by H. Alloul et al. [7] and by specific heat measurements by Loram et al. [8] The pseudogap is also apparent in ARPES (Angle Resolved Photoemission Spectroscopy) and STM (Scanning tunneling microscope) data, which can measure the density of states of ...
The Ingenuity Gap is a popular science book. [10] Homer-Dixon takes an inter-disciplinary approach connecting political science with sociology, economics, history, biology, and ecology. [ 11 ] [ 12 ] [ 13 ] The narrative is structured as a travelogue as the author travels to meet experts and construct his theory. [ 14 ]