Wei Wei, Dai Ying, Huang Baibiao
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.
Phys Chem Chem Phys. 2016 Jun 21;18(23):15632-8. doi: 10.1039/c6cp02741e. Epub 2016 May 25.
In-plane heterostructures of two-dimensional transition-metal dichalcogenides (TMDs) demonstrate the formation of one-dimensional interfaces (or interlines), leading to new exciting properties and device functionalities. In this work, the interfacing effects have been studied in MoS2/WS2 quantum-well and superlattice in-plane heterostructures on the basis of first-principles electronic calculations. In light of the orbital-projected band structures, MoS2/WS2 in-plane heterostructures illustrate type-II band alignments with rather a small band offset for the valence band maximum and a relatively large band offset for the conduction band minimum. Upon increasing the width of TMD constituents, the band gap varies within a small range. In MoS2 and WS2, the surline energy and work function of zigzag edges with S-terminations are obviously higher than those of metal-terminations, and charge transfer from MoS2 to WS2 could be addressed due to the difference in the Fermi level. In-gap levels induced by S vacancies in MoS2/WS2 in-plane heterostructures are discrete and, interestingly, change to consecutive bands due to the built-in electric field.
二维过渡金属二硫属化物（TMDs）的面内异质结构展示了一维界面（或界面线）的形成，从而带来了令人兴奋的新特性和器件功能。在这项工作中，基于第一性原理电子计算，对MoS2/WS2量子阱和超晶格面内异质结构中的界面效应进行了研究。根据轨道投影能带结构，MoS2/WS2面内异质结构呈现II型能带排列，价带最大值处的能带偏移相当小，导带最小值处的能带偏移相对较大。随着TMD组分宽度的增加，带隙在小范围内变化。在MoS2和WS2中，具有S端接的锯齿形边缘的表面线能量和功函数明显高于金属端接的情况，并且由于费米能级的差异，可以确定电荷从MoS2转移到WS2。MoS2/WS2面内异质结构中由S空位诱导的带隙能级是离散的，有趣的是，由于内建电场，这些能级会转变为连续能带。
