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贝芷苡铜虫 (小有名气)
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-U
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许多文献中多提到 negative U property,但是很少给出具体定义，一下为其定义 A defect has negative-U properties if it can trap two electrons (or holes) with the second bound more strongly than the first. The system can be thought of as an extrinsic Cooper pair, the defect providing an environment in which a net attraction can develop between the otherwise Coulombically repulsive carriers. Evidence previously cited for this behavior in selected liquid and solid state systems will be reviewed. Recently, the first direct and unambiguous demonstration of the phenomenon in a solid has been supplied for two simple point defects in crystalline silicon—the lattice vacancy and interstitial boron. The experiments leading to this identification are described and mechanisms for this remarkable phenomenon are discussed. 来自Advances in Solid State Physics, Advances in Solid State Physics, Volume 24. ISBN 978-3-528-08030-3. Friedr.Vieweg & Sohn Braunschweig, 1984, p. 163 |
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