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Theoretical Investigations of Si-Ge Alloys in P42/ncm Phase: First-Principles Calculations

Tianjin Key Laboratory for Civil Aircraft Airworthiness and Maintenance, Civil Aviation University of China, Tianjin 300300, China
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Academic Editor: Giorgio Biasiol
Materials 2017, 10(6), 599; https://doi.org/10.3390/ma10060599
Received: 22 April 2017 / Revised: 15 May 2017 / Accepted: 24 May 2017 / Published: 31 May 2017
(This article belongs to the Section Structure Analysis and Characterization)
The structural, mechanical, anisotropic, electronic and thermal properties of Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase are investigated in this work. The calculations have been performed with an ultra-soft pseudopotential by using the generalized gradient approximation and local density approximation in the framework of density functional theory. The achieved results for the lattice constants and band gaps of P42/ncm-Si and P42/ncm-Ge in this research have good accordance with other results. The calculated elastic constants and elastic moduli of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase are better than that of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/mnm phase. The Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase exhibit varying degrees of mechanical anisotropic properties in Poisson’s ratio, shear modulus, Young’s modulus, and universal anisotropic index. The band structures of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase show that they are all indirect band gap semiconductors with band gap of 1.46 eV, 1.25 eV, 1.36 eV and 1.00 eV, respectively. In addition, we also found that the minimum thermal conductivity κmin of the Si, Si0.667Ge0.333, Si0.333Ge0.667 and Ge in P42/ncm phase exhibit different degrees of anisotropic properties in (001), (010), (100) and (01¯0) planes. View Full-Text
Keywords: Si-Ge alloys; mechanical properties; anisotropic properties; electronic properties Si-Ge alloys; mechanical properties; anisotropic properties; electronic properties
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MDPI and ACS Style

Ma, Z.; Liu, X.; Yu, X.; Shi, C.; Yan, F. Theoretical Investigations of Si-Ge Alloys in P42/ncm Phase: First-Principles Calculations. Materials 2017, 10, 599.

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