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Distorted Janus Transition Metal Dichalcogenides: Stable Two-Dimensional Materials with Sizable Band Gap and Ultrahigh Carrier Mobility
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-08-09 , DOI: 10.1021/acs.jpcc.8b04161
Xiao Tang 1 , Shengshi Li 2 , Yandong Ma 2 , Aijun Du 1 , Ting Liao 1 , Yuantong Gu 1 , Liangzhi Kou 1
Affiliation  

Transition metal dichalcogenides (TMDs) are ideal layered materials to fabricate field effect transistors (FETs) due to their sizable band gaps and high stability, however, the low carrier mobility limits the response speeds. Here, based on recent experimental progress, we employed first principle calculations to reveal a distorted phase of the Janus TMD, 1T′ MoSSe, which is highly stable, exhibiting a moderate band gap and ultrahigh carrier mobility. We show that 1T′ MoSSe can be obtained via structural transition from the synthesized 2H phase after overcoming an energy barrier of 1.10 eV, which can be significantly reduced with alkali metal adsorption, thus proposing a feasible approach for experimental fabrications. 1T′ MoSSe is predicted to be a semiconductor with a trivial band gap of 0.1 eV (based on Heyd–Scuseria–Ernzerhof calculations), which can be closed to form Dirac nodes and then reopened under strain deformation. Due to the almost linear dispersion of the band states, an ultrahigh electron (hole) mobility of up to 1.21 × 105 (7.24 × 104) cm2/V/s is predicted for the new phase, which is 3 orders of magnitudes higher than traditional counterparts and close to the value of graphene. The high stability, sizable band gap, and ultrahigh carrier mobility in the new Janus systems are expected to be used in high-performance electronics applications.

中文翻译:

变形的Janus过渡金属双硫属元素化物:稳定的二维材料,具有较大的带隙和超高的载流子迁移率

过渡金属二硫化碳(TMD)由于其较大的带隙和高稳定性而成为制造场效应晶体管(FET)的理想分层材料,但是,低载流子迁移率限制了响应速度。在这里,基于最近的实验进展,我们采用第一原理计算来揭示Janus TMD 1T'MoSSe的扭曲相位,该相位非常稳定,表现出中等的带隙和超高的载流子迁移率。我们表明,在克服1.10 eV的能垒之后,可以通过从合成的2H相进行结构转变获得1T'MoSSe,该势垒可以通过碱金属吸附显着降低,从而为实验制备提出了一种可行的方法。预计1T'MoSSe是带隙为0.1 eV的半导体(基于Heyd–Scuseria–Ernzerhof计算),可以将其闭合以形成Dirac节点,然后在应变变形下重新打开。由于能带几乎呈线性色散,因此超高电子(空穴)迁移率高达1.21×10对于新相,预测为5(7.24×10 4)cm 2 / V / s,比传统对应物高3个数量级,并且接近石墨烯的值。新型Janus系统中的高稳定性,较大的带隙和超高的载流子迁移率有望用于高性能电子应用。
更新日期:2018-08-10
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