Anisotropic to Isotropic Transition in Monolayer Group-IV Tellurides.
Anisotropic to Isotropic Transition in Monolayer Group-IV Tellurides.
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单层 IV 族碲化物中各向异性到各向同性的转变
DOI：
10.3390/ma14164495
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发表时间：
2021-08-11
期刊：
影响因子：
--
通讯作者：
Lu P
中科院分区：
文献类型：
--
作者：
Wang Q;Wu L;Urban A;Cao H;Lu P
具有磷系衍生结构的单层四族碲化物由于其独特的性质引起了越来越多的研究兴趣。本文采用GW和Bethe-Salpeter方程方法系统地研究了二维iv族碲化物（SiTe, GeTe, SnTe, PbTe）的准粒子电子和光学性质。计算结果表明，除了直接带隙为1.742 eV的单层PbTe外，其余四族碲化物均为间接带隙半导体，且均具有较强的载流子输运能力。我们进一步发现，激子效应对单层iv族碲化物的光学性质有显著影响，预测SiTe的激子结合能高达0.598 eV。有趣的是，单层iv族碲化物的物理性质呈现出越来越各向同性的趋势：从SiTe到PbTe，计算出的准粒子带隙、光隙和进一步的激子束缚能沿不同方向的差异有减小的趋势。我们证明了这些各向异性的电子和光学性质源于结构各向异性，而结构各向异性又是非键电子对之间库仑排斥的结果。我们的理论结果为iv族碲化物单层的各向异性特性提供了更深入的理解。
Monolayer group-IV tellurides with phosphorene-derived structures are attracting increasing research interest because of their unique properties. Here, we systematically studied the quasiparticle electronic and optical properties of two-dimensional group-IV tellurides (SiTe, GeTe, SnTe, PbTe) using the GW and Bethe–Salpeter equation method. The calculations revealed that all group-IV tellurides are indirect bandgap semiconductors except for monolayer PbTe with a direct gap of 1.742 eV, while all of them are predicted to have prominent carrier transport ability. We further found that the excitonic effect has a significant impact on the optical properties for monolayer group-IV tellurides, and the predicted exciton binding energy is up to 0.598 eV for SiTe. Interestingly, the physical properties of monolayer group-IV tellurides were subject to an increasingly isotropic trend: from SiTe to PbTe, the differences of the calculated quasiparticle band gap, optical gap, and further exciton binding energy along different directions tended to decrease. We demonstrated that these anisotropic electronic and optical properties originate from the structural anisotropy, which in turn is the result of Coulomb repulsion between non-bonding electron pairs. Our theoretical results provide a deeper understanding of the anisotropic properties of group-IV telluride monolayers.
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