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首页> 外文期刊>Optical and quantum electronics >Comparison of first principles and semi-empirical models of the structural and electronic properties of Ge_(1-x)Sn_x alloys
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Comparison of first principles and semi-empirical models of the structural and electronic properties of Ge_(1-x)Sn_x alloys

机译：Ge_（1-x）Sn_x合金的结构和电子性能的第一性原理和半经验模型的比较

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摘要

We present and compare three distinct atomistic models-based on first principles and semi-empirical approaches-of the structural and electronic properties of Ge1-xSnx alloys. Density functional theory calculations incorporating Heyd-Scuseria-Ernzerhof (HSE), local density approximation (LDA) and modified Becke-Johnson (mBJ) exchange-correlation functionals are used to perform structural relaxation and electronic structure calculations for a series of Ge1-xSnx alloy supercells. Based on HSE calculations, a semi-empirical valence force field (VFF) potential and sp(3)s* tight-binding (TB) Hamiltonian are parametrised. Comparing the HSE, LDA+mBJ and VFF+TB models, and using the HSE results as a benchmark, we demonstrate that: (1) LDA+mBJ calculations provide an accurate first principles description of the electronic structure at reduced computational cost, (2) the VFF potential is sufficiently accurate to circumvent the requirement to perform first principles structural relaxation, and (3) VFF+TB calculations provide a good quantitative description of the alloy electronic structure in the vicinity of the band edges. Our results also emphasise the importance of Sn-induced band mixing in determining the nature of the conduction band structure of Ge1-xSnx alloys. The theoretical models and benchmark calculations we present inform and enable predictive, computationally efficient and scalable atomistic calculations for disordered alloys and nanostructures. This provides a suitable platform to underpin further theoretical investigations of the properties of this emerging semiconductor alloy.
机译：我们提出并比较了三种基于第一性原理和半经验方法的Ge1-xSnx合金的结构和电子性能的不同原子模型。结合Heyd-Scuseria-Ernzerhof（HSE），局部密度近似（LDA）和改良的Becke-Johnson（mBJ）交换相关泛函的密度泛函理论计算可用于执行一系列Ge1-xSnx合金的结构弛豫和电子结构计算超级细胞。基于HSE计算，对半经验价电场（VFF）势和sp（3）s *紧束缚（TB）哈密顿量进行参数化。比较HSE，LDA + mBJ和VFF + TB模型，并以HSE结果作为基准，我们证明：（1）LDA + mBJ计算以降低的计算成本为电子结构提供了准确的第一性原理描述，（2 ）VFF电位足够准确，可以规避执行基本原理结构弛豫的要求，并且（3）VFF + TB计算可很好地定量描述带边缘附近的合金电子结构。我们的结果还强调了Sn诱导能带混合在确定Ge1-xSnx合金导带结构性质方面的重要性。我们目前提供的理论模型和基准计算为无序合金和纳米结构提供了可预测，计算高效且可扩展的原子计算信息，并使之成为可能。这提供了合适的平台，以支持对该新兴半导体合金的性能进行进一步的理论研究。

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