Nanoscale structure of microvoids in a-Si:H: a first-principles study
Nanoscale structure of microvoids in a-Si:H: a first-principles study
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a-Si:H 中微孔的纳米级结构：第一性原理研究
DOI：
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发表时间：
2015
期刊：
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通讯作者：
S. Elliott
中科院分区：
文献类型：
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作者：
P. Biswas;S. Elliott
在本文中，我们研究了氢化非晶硅（a-Si:H）中原子微孔的形状、尺寸和数量密度。通过联合使用实验红外数据和从头算模拟，我们提出了一种简单有效的氢化方案，能够产生用于研究微孔的大型 a-Si:H 原子模型。我们的结果表明，网络中的氢原子分布在稀疏（或孤立）和聚集的环境中。对于含有 9-14 at.% 氢的 a-Si:H 模型，我们发现总氢原子的大约 3-4 at.% 分布在孤立相中。发现簇状相的密度在 6-12 at.% 之间，这似乎取决于网络中氢的含量。原子微孔回转半径的计算表明，微孔的直径分布在6 Å到12 Å之间。在我们的研究中，还观察到微孔内部形成了一些氢分子，其浓度相对于硅原子约为 1 at.%。我们将我们的结果与小角 X 射线散射 (SAXS)、红外 (IR) 吸收、核磁共振 (NMR) 和量热研究的结果进行了比较。
In this paper, we have studied the shape, size, and number density of atomic microvoids in hydrogenated amorphous silicon (a-Si:H). By jointly employing experimental infrared data and ab initio simulations, we propose a simple and effective hydrogenation scheme, which is capable of producing large atomistic models of a-Si:H for studying microvoids. Our results suggest that hydrogen atoms in the networks are distributed in sparse (or isolated) and clustered environments. For a-Si:H models with 9–14 at.% hydrogen, we find approximately 3–4 at.% of total hydrogen atoms are distributed in the isolated phase. The density of the clustered phase is found to be between 6–12 at.%, which appears to depend on the amount of hydrogen in the network. The calculation of radii of gyration of atomic microvoids shows that the diameter of the microvoids is distributed from 6 Å to 12 Å. A few hydrogen molecules have also been observed to form inside the microvoids in our study, the concentration of which is about 1 at.% relative to silicon atoms. A comparison of our results with those from small-angle x-ray scattering (SAXS), infrared (IR) absorption, nuclear magnetic resonance (NMR) and calorimetric studies are presented.