Optical enhancement of dielectric permittivity in reduced lanthanum aluminate
Optical enhancement of dielectric permittivity in reduced lanthanum aluminate
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还原铝酸镧介电常数的光学增强
DOI：
10.1103/physrevb.101.184114
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发表时间：
2020
影响因子：
3.7
通讯作者：
Taniguchi Hiroki
中科院分区：
文献类型：
--
作者：
Nagai Takayuki;Kuwabara Akihide;Kumagai Yu;Terasaki Ichiro;Taniguchi Hiroki
当光在固体中被吸收时，电导率通常通过光掺杂的导电载体的产生而增强，称为光电导。在这里，我们表明，紫外光吸收抑制光电导，但显着提高介电常数的陶瓷样品的缺陷故意引入还原合成。使用系统的光照射下的介电测量结合计算研究的缺陷形成能量，我们解释这种非常规的光致现象的光激发偶极子：光激发的电子被困在间隙状态引入的氧空位，而光激发的空穴本地化的价带最大值。因此，所产生的电子-空穴对充当电偶极子以增强介电常数。这种前所未有的光电效应不仅为介电材料提供了替代功能，而且为下一代光电器件铺平了道路。
When light is absorbed in solids, electrical conductivity is usually enhanced through generation of photodoped conductive carriers, known as photoconduction. Here we show UV-light absorption restrains photoconduction, but markedly enhances dielectric permittivity in a ceramic sample ofwith defects introduced deliberately by reduction synthesis. Using systematic dielectric measurements under photoirradiation combined with computational studies for defect formation energies, we explain this unconventional photoinduced phenomenon in terms of photoexcited dipoles: The photoexcited electrons are trapped in in-gap states introduced by oxygen vacancies whereas photoexcited holes are localized in a valence-band maximum. Thus the created electron-hole pair acts as an electric dipole to enhance the dielectric permittivity. This unprecedented photoelectric effect does not only provide an alternative functionality for dielectric materials, but also paves the way for next-generation photoelectronic devices.