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  • 濮春英,周大伟,吕林霞,王卓,唐鑫.二维BX(X=S,Se,Te)结构预测与性质的第一性原理研究[J].低温物理学报,2019,(3):204-212.    [点击复制]
  • PUChunying,ZHOUDawei,LVLinxia,WANGZhuo,TANGXin.Structural Searching and Properties for Two Dimensional BX(X=S, Se, and Ga) from First-principles Calculations[J].LOW TEMPERATURE PHYSICAL LETTERS,2019,(3):204-212.   [点击复制]
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二维BX(X=S,Se,Te)结构预测与性质的第一性原理研究
濮春英1, 周大伟1, 吕林霞1, 王卓2, 唐鑫3
0
(1.南阳师范学院,物理与电子工程学院,南阳 473061;2.南阳师范学院,机械电子工程学院,南阳 473061;3.桂林理工大学,材料科学与工程学院,桂林 541004)
摘要:
采用基于粒子群优化算法的结构预测程序CALYPSO结合密度泛函理论的VASP软件包,预测得到二维BX(X=S、Se、Te)的最低能量结构,该结构是由B和X原子形成的双层褶皱的六角密堆积结构,层与层之间较强的B-B键是稳定结构的关键.凝聚能和声子谱计算结果表明二维BX(X=S、Se、Te)在热力学和动力学上均是稳定的.能带结构和电子态密度的计算分析发现三种二维材料均呈现间接带隙半导体行为,带隙分别为3.98 eV(BS)、3.84 eV(BSe)和2.31 eV(BTe). 采用“应力应变”方法,计算得到二维BX(X=S、Se、Te)的弹性常数、杨氏模量、泊松比以及杨氏模量和泊松比随方向变化的关系并进行了详细的讨论, 发现杨氏模量和泊松比呈现各向同性. 除此之外,我们还研究了二维BX(X=S、Se、Te)的应力-应变关系,发现BTe较BS和BSe有较强的抗拉伸性.由于BS和BSe在价带顶有效质量较大,为此,我们采用形变势理论研究了BTe的载流子迁移率. 结果发现BTe在ao1和ao2方向上的电子迁移率分别为20.8和122.6 cm2V-1s-1,而空穴在两个方向上的迁移率分别为673.4和65.0 cm2V-1s-1, 空穴在ao1方向上的较高的迁移率说明二维BTe具有较好的输运性质.
关键词:  结构预测,电子结构,力学性质,载流子迁移率
DOI:10.13380/j.ltpl.02019.03.009
基金项目:
Structural Searching and Properties for Two Dimensional BX(X=S, Se, and Ga) from First-principles Calculations
PUChunying1, ZHOUDawei1, LVLinxia1, WANGZhuo2, TANGXin3
(1.College of Physics and Electronic Engineering, Nanyang Nomal University, Nanyang 473061, China;2.College of Mechanical and Electronic Engineering, Nanyang Nomal University, Nanyang 473061, China;3.College of Material Science and Engineering, Guilin University of Technology, Guilin 541004, China)
Abstract:
By means of the particle swarm optimization algorithm and density functional theory on two dimensional (2D) BX (X=S, Se, and Te) structure prediction, we predicted that the lowest-energy structures of 2D BX exhibit bilayer buckled stacking systems and the strong B-B bond is vital to structural stability. To clarify the stability of 2D BX bilayer, we estimated their cohesive energies and phonon dispersion. Compared the cohesive energies with that of silicene and germanene, the higher cohesive energies in three compounds and real frequencies in the whole Brillouin zone of 2D BX implied that 2D BX are strongly bonded network with high stability. A hybrid functional of Heyd-Scuseria-Ernzerhof (HSE06) calculations to calculate the band structures of 2D BX structures indicate that the three compounds are semiconductors with indirect band gap energies of 3.98 eV(BS), 3.84 eV(BSe), and 2.31 eV(BTe). The calculations of elastic constants, Young’s modulus, shear modulus, Poisson ratio, together with the direction dependence of Young’s modulus and Poisson ratio in-plane indicate that the Young’s modulus and Poisson ratio exhibit isotropic. To estimate the elastic limit of 2D BX, we calculated the surface tension of 2D BX and graphene to be compared as a functional of tensile strain. The predicted elastic strain limit suggest that 2D BX bilayers are highly flexible and may have potenital applications in flexible display. Furthermore, Based on the deformation potential theory, the 2D BTe have electron mobilities (20.8 along ao1 direction and 122.6 cm2V-1s-1 along ao2 direction, respectively) and hole mobilities (673.4 along ao1 direction and 65.0 cm2V-1s-1 along ao2 direction, respectively) shown anisotropic in-plane. The higher hole mobility along ao1 direction indicates that BTe have good transport property.
Key words:  Structure searching, Electronic structure, Mechanical properties, Carrier mobility.

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