二维异质结MoS_2/WSe_2能带排列的第一性原理研究
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摘要
由于二维材料具有丰富的物理化学性质,比如在场效应管、薄膜电路等低微纳米器件上有巨大的潜在应用价值,从而吸引了研究者们的广泛关注和兴趣.本文中,我们采用第一性原理方法,对两种二维材料MoS_2和WSe_2组成的一种新形式的异质结进行能带排列方面的探索.首先,我们将两种材料堆叠成垂直方向,增大层间距,考察基本没有相互作用时的能带排列.然后,我们分别考察MoS_2/MoS_2-WSe_2以及WSe_2/WSe_2-MoS_2两种结构.结果发现,在组成异质结材料之后,层间的弱相互作用对两个组分材料的能带和态密度都有非常重要的影响.随着双层区域尺寸的增加,其价带顶和导带底都会有连续的变化,能带排列趋于安德森极限.此理论工作,将有助于人们理解各种类型的二维异质结能带排列情况,进而帮助理解低维器件的性能变化.
Two-dimensional materials attracted many interesting because of the excellent physical and chemical properties,and the huge potential applications as field effect and super thin circuits. In this paper,we investigate the band offset in a two-dimensional MoS_2/WSe_2 heterostructures under a two-step method,by using the first-principle calculations. We found the weak interaction between the layers have the important impact on the band structure and density of states. With the increase of the bilayer length,the band offset will approach to Anderson limits. This work will help us to better understand the band offset and the performance in device designed by two dimensional heterostructures.
Two-dimensional materials attracted many interesting because of the excellent physical and chemical properties,and the huge potential applications as field effect and super thin circuits. In this paper,we investigate the band offset in a two-dimensional MoS_2/WSe_2 heterostructures under a two-step method,by using the first-principle calculations. We found the weak interaction between the layers have the important impact on the band structure and density of states. With the increase of the bilayer length,the band offset will approach to Anderson limits. This work will help us to better understand the band offset and the performance in device designed by two dimensional heterostructures.
引文
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[2] Mannix A J,Zhou X F,Kiraly B,et al. Synthesis of borophenes:Anisotropic,two-dimensional boron polymorphs[J]. Science,2015,350(6267):1513.
[3] Anasori B,Lukatskaya M R,Gogotsi Y. 2D metal carbides and nitrides(MXenes)for energy storage[J]. Nature Rev Mater,2017,2 16098.
[4] Li L,Yu Y,Ye G L,et al. Black phosphorus field-effect transistors[J]. Nature Nanotechnol,2014,9:372.
[5] Mak K F,Lee C,Hone J,et al. Atomically thin Mo S2:A new direct-gap semiconductor[J]. Physical Review Letters,2010,105(13):136805.
[6] Fang H,Chuang S,Chang T C,et al. High-performance single layered WSe2p-FETs with chemically doped contacts[J]. Nano letters,2012,12(7):3788.
[7] Song L,Ci L,Lu H,et al. Large scale growth and characterization of atomic hexagonal boron nitride layers[J]. Nano Lett,2010,10(8):3209.
[8] Gong C,Li L,Li Z,et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals[J]. Nature,2017,546 265.
[9] Huang B,Clark G,Navarro-Moratalla E,et al. Lyer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit[J]. Nature,2017,546:270.
[10] Ling X,Lin Y,Ma Q,et al. Parallel Stitching of 2D Materials[J]. Adv Mater,2016,28(12):2322.
[11] Lee C H,Lee G H,van der Zande A M,et al. Atomically thin p-n junctions with van der Waals heterointerfaces[J]. Nature Nanotechnol,2014,9:676.
[12] Kresse G,Joubert D. From ultrasoft pseudopotentials to the projector augmented-wave method[J]. Phys Rev B,1999,59(3):1758.
[13] Kresse G,Furthmüller J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set[J]. Comp Mater Sci,1996,6(1):15.
[14] Perdew J P,Burke K,Ernzerhof M. Generalized gradient approximation made simple[J]. Phys Rev Lett,1996,77(18):3865.
[15] Zhang J,Xie W,Zhao J,et al. Band alignment of two-dimensional lateral heterostructures[J]. 2D Materials,2016,4(1):015038.
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