Theory of band gap bowing of disordered substitutional II–VI and III–V semiconductor alloys
Theory of band gap bowing of disordered substitutional II–VI and III–V semiconductor alloys
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无序取代 II-VI 和 III-V 半导体合金的带隙弯曲理论
DOI：
10.1140/epjb/e2012-21064-9
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
G. Czycholl
中科院分区：
文献类型：
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作者：
D. Mourad;G. Czycholl
对于一类广泛的技术相关的化合物III-V和II-VI半导体材料，可以实现AxB1、−、XC型AC和BC混晶(合金)。由于体带隙等电学性质随着x的变化而不断变化，只要选择合适的浓度x，就可以得到纯AC和BC系统之间的任何带隙，只要它们的比例是可混溶的，热力学上是稳定的。在大多数情况下，带隙不随x线性变化，但观察到明显的弯曲行为作为浓度的函数。本文从纯AC和BC系的经验紧束缚模型出发，证明了这种−-XC半导体的电子性质，特别是禁带弯曲可以很好地描述和理解。用概率x和1−x分别选取AC系和BC系的紧束缚参数可以描述AxB1-−-xC体系的电学性质。我们通过有限但大的超晶胞的精确对角化和在已建立的相干势近似下的计算来证明这一点。我们将这种处理应用于II-VI系统Cd_xZn_1−_xSe，III-V系统InxGa_1−_xAs和III-氮化物系统GaxAl_1−_xN。
For a wide class of technologically relevant compound III–V and II–VI semiconductor materials AC and BC mixed crystals (alloys) of the type AxB1−xC can be realized. As the electronic properties like the bulk band gap vary continuously withx, any band gap in between that of the pure AC and BC systems can be obtained by choosing the appropriate concentrationx, granted that the respective ratio is miscible and thermodynamically stable. In most cases the band gap does not vary linearly withx, but a pronounced bowing behavior as a function of the concentration is observed. In this paper we show that the electronic properties of such AxB1−xC semiconductors and, in particular, the band gap bowing can well be described and understood starting from empirical tight-binding models for the pure AC and BC systems. The electronic properties of the AxB1−xC system can be described by choosing the tight-binding parameters of the AC or BC system with probabilitiesxand 1 −x, respectively. We demonstrate this by exact diagonalization of finite but large supercells and by means of calculations within the established coherent potential approximation (CPA) We apply this treatment to the II–VI system CdxZn1−xSe, to the III–V system InxGa1−xAs and to the III-nitride system GaxAl1−xN.