二维MoSi_(2)N_(4)/WSe_(2)异质结的第一性原理研究

First⁃principles study of two-dimensional MoSi_(2)N_(4)/WSe_(2)heterostructure

实验上新合成的MoSi_(2)N_(4)(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WSe_(2)(WS)垂直堆垛而成的二维MSN/WS异质结并基于第一性原理计算对其电子性质进行了计算,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.

The experimentally newly synthesized MoSi_(2)N_(4)(MSN)has attracted much attention due to its unique septuple-atomic layers structure and electronic properties.In this work,a two-dimensional MSN/WS hetero⁃structure stacked by a two-dimensional MSN vertically with a two-dimensional WSe_(2)(WS)is constructed and its electronic properties is calculated based on the first-principles calculations,which exhibits direct gap semi⁃conductor 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 hetero⁃structure.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 band gap semiconductor and type-I band alignment properties.Under the negative biaxial strain,the MSN/WS hetero⁃structure changes from the original direct bandgap semiconductor to the indirect band gap semiconductor,and when the applied negative biaxial strain reaches-6%and-8%,the type-I band alignment changes to the type II band alignment.