Tran Tuan-Anh, Hai Le S, Nguyen Cuong Q, Vi Vo T T, Linh Tran P T, Hieu Nguyen N
Faculty of Applied Sciences, Ho Chi Minh City University of Technology and Education Ho Chi Minh City Vietnam
Institute of Research and Development, Duy Tan University Da Nang Vietnam
RSC Adv. 2023 Feb 28;13(10):6838-6846. doi: 10.1039/d2ra08012e. eCollection 2023 Feb 21.
In this paper, we introduce a new phase of two-dimensional aluminum monochalcogenide, namely -AlX (X = S, Se, and Te). With the space group, -AlX possesses a large unit cell containing 8 atoms. The phase of AlX monolayers is found to be dynamically and elastically stable based on the evaluation of its phonon dispersions and elastic constants. The anisotropic atomic structure of -AlX leads to a strong anisotropy in its mechanical properties with Young's modulus and Poisson's ratio strongly dependent on the directions examined in the two-dimensional plane. All three monolayers of -AlX are found to be direct band gap semiconductors, which are compared with the indirect band gap semiconductors of available -AlX. Particularly, the transition from direct to indirect band gap is observed in -AlX when a compressive biaxial strain is applied. Our calculated results indicate that -AlX exhibits anisotropic optical characteristics and its absorption coefficient is high. Our findings suggest that -AlX monolayers are suitable for applications in next-generation electro-mechanical and anisotropic opto-electronic nanodevices.
在本文中，我们介绍了二维单硫族化铝的一个新相，即γ-AlX（X = S、Se和Te）。具有γ空间群的γ-AlX拥有一个包含8个原子的大晶胞。基于对其声子色散和弹性常数的评估，发现AlX单层的γ相在动力学和弹性方面是稳定的。γ-AlX的各向异性原子结构导致其力学性能具有很强的各向异性，杨氏模量和泊松比强烈依赖于在二维平面中所考察的方向。发现所有三种γ-AlX单层都是直接带隙半导体，这与现有的α-AlX间接带隙半导体形成对比。特别地，当施加压缩双轴应变时，在α-AlX中观察到从直接带隙到间接带隙的转变。我们的计算结果表明，γ-AlX表现出各向异性光学特性且其吸收系数很高。我们的研究结果表明，γ-AlX单层适用于下一代机电和各向异性光电子纳米器件。
