Dielectric properties of hexagonal boron nitride and transition metal dichalcogenides: from monolayer to bulk
Dielectric properties of hexagonal boron nitride and transition metal dichalcogenides: from monolayer to bulk
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DOI：
10.1038/s41699-018-0050-x
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发表时间：
2018-03-08
影响因子：
9.7
通讯作者：
Vandenberghe, William G.
中科院分区：
文献类型：
--
作者：
Laturia, Akash;Van de Put, Maarten L.;Vandenberghe, William G.
六方氮化硼（h-BN）和半导体过渡金属二硫族化合物（TMDs）有望极大地改善未来规模电子器件的静电控制。为了量化这些材料在器件中的前景，我们从第一性原理计算了三角棱柱和八面体配位的tmd以及h-BN的面外和面内介电常数，厚度范围从单层到双层到块体。计算了离子和电子对介电响应的贡献。我们的计算表明，过渡金属二硫族化合物的面外介电响应主要由其电子分量决定，并且介电常数随碳原子序数的增加而增加。总的来说，随着层数从单层增加到块体，TMDs和h-BN的面外介电常数增加了约15%，而面内分量保持不变。我们的计算还表明，对于八面体配位的tmd，离子（静态）对介电响应的贡献在平面方向上非常高（电子贡献的4.5倍）。这表明，在四方相的半导体tmd将遭受过度的极光学散射，从而恶化其电子输运性质。
Hexagonal boron nitride (h-BN) and semiconducting transition metal dichalcogenides (TMDs) promise greatly improved electrostatic control in future scaled electronic devices. To quantify the prospects of these materials in devices, we calculate the out-of-plane and in-plane dielectric constant from first principles for TMDs in trigonal prismatic and octahedral coordination, as well as for h-BN, with a thickness ranging from monolayer and bilayer to bulk. Both the ionic and electronic contribution to the dielectric response are computed. Our calculations show that the out-of-plane dielectric response for the transition-metal dichalcogenides is dominated by its electronic component and that the dielectric constant increases with increasing chalcogen atomic number. Overall, the out-of-plane dielectric constant of the TMDs and h-BN increases by around 15% as the number of layers is increased from monolayer to bulk, while the in-plane component remains unchanged. Our computations also reveal that for octahedrally coordinated TMDs the ionic (static) contribution to the dielectric response is very high (4.5 times the electronic contribution) in the in-plane direction. This indicates that semiconducting TMDs in the tetragonal phase will suffer from excessive polar-optical scattering thereby deteriorating their electronic transport properties.