二维MoSi2N4WSe2异质结的第一性原理研究

实验上新合成的MoSi2N4（MSN）由于其独特的七原子层结构和电子特性引起了人们的广泛关注。本文搭建了一种由二维MSN与二维WSe2（WS）垂直堆垛而成的二维MSN/WS异质结，其表现出直接间隙半导体和I型能带排列的特性，具有1.46 eV的带隙。在异质结界面处存在一个由电荷耗尽层MSN指向电荷积累层WS微弱的内建电场。最后，通过施加双轴应变对二维MSN/WS异质结进行调控。发现在正双轴应变的作用下，MSN/WS异质结保持了原来直接带隙半导体和I型能带排列特性；在负双轴应变作用下，MSN/WS异质结由原来的直接带隙半导体转变为间接带隙半导体，当施加的负双轴应变达到-6%与-8%时，I型能带排列转变为Ⅱ型能带排列。

First-principles Study of Two-dimensional MoSi2N4/WSe2 Heterostructure

The experimentally newly synthesized MoSi2N4 (MSN) has attracted much attention due to its unique septuple-atomic layers structure and electronic properties. In this work, a two-dimensional MSN/WS heterostructure stacked by a two-dimensional MSN vertically with a two-dimensional WSe2 (WS) is constructed, which exhibits direct gap semiconductor properties with a band gap of 1.46 eV and type-I band alignment. A weak built-in electric field from the charge depletion layer MSN to the charge accumulation layer WS exists at the interface of the heterostructure. Finally, the two-dimensional MSN/WS heterostructure is modulated by applying the biaxial strain. It is found that under the positive biaxial strain, the MSN/WS heterostructure maintains the original direct bandgap semiconductor and type-I band alignment properties. Under the negative biaxial strain, the MSN/WS heterostructure changes from the original direct bandgap semiconductor to the indirect bandgap semiconductor, and when the applied negative biaxial strain reaches -6% and -8%, the type-I band alignment changes to the type II band alignment.