Dielectric discontinuity at interfaces in the atomic-scale limit: Permittivity of ultrathin oxide films on silicon
Dielectric discontinuity at interfaces in the atomic-scale limit: Permittivity of ultrathin oxide films on silicon
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DOI：
10.1103/physrevlett.91.267601
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发表时间：
2003-12-31
影响因子：
8.6
通讯作者：
Pasquarello, A
中科院分区：
文献类型：
--
作者：
Giustino, F;Umari, P;Pasquarello, A
使用密度泛函方法，我们研究了介电常数跨越界面在原子尺度上。聚焦于静态和高频的SiO2薄膜的硅，氧化物厚度从12埃下降到原子尺度，我们发现偏离体值在雅阁与实验。一个经典的三层模型占计算的折射率，并支持跨界面的微观极化曲线。局部屏蔽在对应于第一近邻距离的长度尺度上变化，表明介电转变受化学分级的支配。硅诱导的间隙状态所示，发挥次要作用。
Using a density-functional approach, we study the dielectric permittivity across interfaces at the atomic scale. Focusing on the static and high-frequency permittivities of SiO2 films on silicon, for oxide thicknesses from 12 Angstrom down to the atomic scale, we find a departure from bulk values in accord with experiment. A classical three-layer model accounts for the calculated permittivities and is supported by the microscopic polarization profile across the interface. The local screening varies on length scales corresponding to first-neighbor distances, indicating that the dielectric transition is governed by the chemical grading. Silicon-induced gap states are shown to play a minor role.