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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Correlation between bond distortion and the band-tail electronic density of states in amorphous silicon: a tight-binding recursion study
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Correlation between bond distortion and the band-tail electronic density of states in amorphous silicon: a tight-binding recursion study

机译：非晶硅中键畸变与带状电子态的密度之间的关系：紧密结合的递归研究

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We study the spatial structure of the electronic states in amorphous silicon using a tight-binding Hamiltonian and the recursion method. A realistic cluster consisting of 4096 atoms in a periodic cubic supercell, obtained using reverse Monte-Carlo methods, is used as a model of amorphous silicon [B.R. Djordjevic, M.F. Thorpe, F. Wooten, Phys. Rev. B 52 (1995) 5685]. The local density of states for each of the 16384 orbitals is computed. Our aim is to provide some insight into the nature of the band tail states and we particularly address the following issues. We examine the relative contributions of the p-orbitals and the s-orbitals to the density of states in the region of the band tail and gap. We investigate the geometric nature of these states. Finally, we study the correlation between the structural distortions in the amorphous silicon cluster and the spatial distribution of the band tail and gap states. Our results show that the p-orbitals contribute a large fraction of the density of states in the valence band tail. This fraction decreases as the energy increases across the gap into the conduction band. We observe the expected change from extended states deep in the valence and conduction band to localized states in the band gap. An attempt was made to characterize this change in terms of the fraction of the total density of states required for a percolating nearest-neighbor path in the cluster as a function of the energy. No abrupt change was observed in this quantity for energies in the region of the band tails. Although there are 4096 atoms in the cluster. 90% of the density of states in the band tail and gap is localized on only 416 atoms, that is, we find a backbone of atoms in the cluster responsible for a large fraction of the states in this energy range. We also find a strong correlation between atoms contributing a high density of states in the band tail and gap region and atoms with a large bond angle distortion. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 30]
机译：我们使用紧密结合的哈密顿量和递归方法研究了非晶硅中电子态的空间结构。使用逆蒙特卡洛方法获得的，由周期性立方超级电池中的4096个原子组成的实际簇用作非晶硅的模型[B.R. Djordjevic，M.F.索普（F. Wooten），物理学B 52（1995）5685]。计算每个16384轨道的状态局部密度。我们的目的是对带尾态的性质提供一些见识，特别是解决以下问题。我们检查了p轨道和s轨道对带尾和带隙区域中状态密度的相对贡献。我们研究了这些状态的几何性质。最后，我们研究了非晶硅团簇中的结构变形与带尾和带隙态的空间分布之间的相关性。我们的结果表明，p轨道对价带尾部的态密度贡献很大。随着能量跨隙进入导带的能量增加，该分数减小。我们观察到了从价态和导带深处的扩展状态到带隙中的局部状态的预期变化。尝试根据渗透的最接近邻居路径所需的状态总密度的分数来表征这种变化，该状态是能量的函数。对于带尾区域中的能量，未观察到该量的突然变化。尽管簇中有4096个原子。带尾和带隙中的状态密度的90％仅位于416个原子上，也就是说，我们发现簇中的原子主链负责该能级范围内的大部分状态。我们还发现，在带尾和能隙区域中贡献高态密度的原子与具有大键角畸变的原子之间具有很强的相关性。 （C）2000 Elsevier Science B.V.保留所有权利。 [参考：30]

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