Effects of stacking order, layer number and external electric field on electronic structures of few-layer C2N-h2D.
Effects of stacking order, layer number and external electric field on electronic structures of few-layer C2N-h2D.
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DOI：
10.1039/c5nr03895b
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发表时间：
2015-08
期刊：
影响因子：
6.7
通讯作者：
Ruiqi Zhang;Bin Li;Jinlong Yang
中科院分区：
文献类型：
--
作者：
Ruiqi Zhang;Bin Li;Jinlong Yang
最近，已经使用简单的湿化学反应合成了一种新型的二维层状材料，即氮化多孔二维结构C2 N-h2 D，并用于制造场效应晶体管器件（Nat.Commun.，2015，6，6486）。在这里，我们进行了第一性原理研究的电子性质的少层C2 N-h2 D与不同的堆叠顺序和层数。由于层间的耦合主要是轨道相互作用，该体系的能带结构，特别是能带和带隙的分裂，取决于其层间的堆积顺序，并且带隙随层数的增加呈现单调减小的行为。所有的少层C2 N-h2 D材料都具有直接带隙的特性，而不考虑在我们的计算中检查的堆叠顺序和层数。体C2 N-h2 D具有间接或直接带隙，这取决于堆叠顺序。此外，当我们在少层C2 N-h2 D上施加面外电场时，除了单层的情况外，由于巨斯塔克效应，其带隙会随着电场的增加而减小，并且在适当的电场下，多层的少层C2 N-h2 D甚至会发生超导体到金属的转变。层状C2 N-h2 D材料由于其禁带宽度可调，在纳米电子和光电子器件中具有广阔的应用前景。
Recently, a new type of two-dimensional layered material, i.e. a nitrogenated holey two-dimensional structure C2N-h2D, has been synthesized using a simple wet-chemical reaction and used to fabricate a field-effect transistor device (Nat. Commun., 2015, 6, 6486). Here we have performed a first-principles study of the electronic properties of few-layer C2N-h2D with different stacking orders and layer numbers. Because of the interlayer coupling mainly in terms of the orbital interaction, band structure of this system, especially splitting of the bands and band gap, depends on its stacking order between the layers, and the band gap exhibits monotonically decreasing behavior as the layer number increases. All the few-layer C2N-h2D materials have characteristics of direct band gap, irrespective of the stacking order and layer number examined in our calculations. And bulk C2N-h2D has an indirect or direct band gap, depending on the stacking order. Besides, when we apply an out-of-plane electric field on few-layer C2N-h2D, its band gap will decrease as the electric field increases due to a giant Stark effect except for the monolayer case, and even a semiconductor-to-metal transition may occur for few-layer C2N-h2D with more layers under an appropriate electric field. Owing to their tunable band gaps in a wide range, the layered C2N-h2D materials will have tremendous opportunities to be applied in nanoscale electronic and optoelectronic devices.