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首页> 外文期刊>Physical review. B, Condensed Matter And Materals Physics >Lattice dynamics of the mixed semiconductors (Be,Zn)Se from first-principles calculations
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Lattice dynamics of the mixed semiconductors (Be,Zn)Se from first-principles calculations

机译：从第一性原理计算混合半导体（Be，Zn）Se的晶格动力学

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摘要

Vibration properties of Zn_(1-x)Be_xSe, a mixed Ⅱ-Ⅵ semiconductor characterized by a high contrast in elastic properties of its pure constituents ZnSe and BeSe, are simulated by first-principles calculations of electronic structure, lattice relaxation, and frozen phonons. The calculations within the local density approximation have been done with the SIESTA method, using norm-conserving pseudopotentials and localized basis functions; the benchmark calculations for pure end systems were, moreover, done also by the all-electron wien2k code. An immediate motivation for the study was to analyze, at the microscopic level, the appearance of anomalous phonon modes detected early in Raman spectra in the intermediate region (20%-80%) of ZnBe concentration. This was discussed early on the basis of a percolation phenomenon-i.e., the result of the formation of wall-to-wall-Be-Se- chains throughout the crystal. The presence of such chains was explicitly allowed in our simulation and indeed brought about a softening and splitting off of particular modes, in accordance with experimental observation, due to a relative elongation of Be-Se bonds along the chain as compared to those involving isolated Be atoms. The variation of force constants with interatomic distances shows common trends in relative independence of the short-range order.
机译：通过电子结构，晶格弛豫和冷冻声子的第一性原理模拟，Zn_（1-x）Be_xSe是一种混合的Ⅱ-Ⅵ半导体，其纯组分ZnSe和BeSe的弹性特性具有很高的对比度，其振动特性得到了模拟。 。局部密度近似值的计算是通过SIESTA方法进行的，使用了范数守恒伪势和局部基函数。此外，纯终端系统的基准计算也通过全电子wien2k代码完成。该研究的直接动机是在微观水平上分析在ZnBe浓度中间区域（20％-80％）的拉曼光谱中早期发现的异常声子模式的出现。这是在渗滤现象的基础上进行了较早的讨论，即整个晶体中壁对壁Be-Se链形成的结果。根据我们的实验观察，这种链明确地允许存在于我们的模拟中，并确实导致了特定模式的软化和分裂，这是由于与链中孤立的Be相比，Be-Se键沿链的相对伸长原子。力常数随原子间距离的变化显示了短程相对独立性的共同趋势。

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