McKenna Keith P, Shluger Alexander L
Department of Physics and Astronomy and The London Centre for Nanotechnology, University College London, Gower Street, London, WC1E 6BT, UK.
Nat Mater. 2008 Nov;7(11):859-62. doi: 10.1038/nmat2289. Epub 2008 Oct 12.
The trapping of electrons by grain boundaries in semiconducting and insulating materials is important for a wide range of physical problems, for example, relating to: electroceramic materials with applications as sensors, varistors and fuel cells, reliability issues for solar cell and semiconductor technologies and electromagnetic seismic phenomena in the Earth's crust. Surprisingly, considering their relevance for applications and abundance in the environment, there have been few experimental or theoretical studies of the electron trapping properties of grain boundaries in highly ionic materials such as the alkaline earth metal oxides and alkali halides. Here we demonstrate, by first-principles calculations on MgO, LiF and NaCl, a qualitatively new type of electron trapping at grain boundaries. This trapping is associated with the negative electron affinity of these materials and is unusual as the electron is confined in the empty space inside the dislocation cores.
在半导体和绝缘材料中，晶界对电子的俘获对于广泛的物理问题至关重要，例如：应用于传感器、压敏电阻和燃料电池的电子陶瓷材料；太阳能电池和半导体技术的可靠性问题；以及地壳中的电磁地震现象。令人惊讶的是，考虑到它们在环境中的应用相关性和丰富性，对于诸如碱土金属氧化物和碱金属卤化物等高离子性材料中晶界的电子俘获特性，很少有实验或理论研究。在此，我们通过对氧化镁、氟化锂和氯化钠进行第一性原理计算，证明了晶界处一种定性的新型电子俘获。这种俘获与这些材料的负电子亲和性相关，并且不同寻常之处在于电子被限制在位错核心内部的空穴中。
