层状graphene/WSSe范德瓦耳斯异质结电子特性和界面接触的理论研究

Theoretical Study on Electronic Properties and Interfacial Contact of Layered Graphene/WSSe Van der Waals Heterojunction

利用第一性原理计算方法研究了层间距和外部电场对graphene/WSSe范德瓦耳斯异质结的电子特性和界面接触的影响规律。由于范德瓦耳斯力作用,graphene和WSSe单层的电子特性可以被保留在graphene/WSSe异质结中。当形成graphene/WSSe异质结时,在石墨烯的狄拉克锥中可以发现小的带隙值(7 meV)。电荷转移产生的内建电场在有效阻碍光激发载流子复合中起着关键作用。与两个独立单层相比,graphene/WSSe异质结在可见光区域具有增强的光吸收,在光电子器件中展现出了潜在应用价值。此外,graphene/WSSe异质结在平衡层间距处显示出n型肖特基接触特性。层间距和外部电场都可以用来改变graphene/WSSe异质结的肖特基势垒高度和接触类型,并有效调节graphene狄拉克锥的位置。本文研究内容为graphene/WSSe异质结在纳米电子和光电子器件领域的应用提供理论依据。

The electronic properties and interface contact of graphene/WSSe van der Waals heterojunction by means of tuning the interlayer distance and external electric field were studied by the first-principles calculation method. The electronic properties of constituent monolayers can be retained in graphene/WSSe heterojunction because of the van der Waals force. A small band gap value(7 meV) can be found in the Dirac cone of graphene in graphene/WSSe heterojunction. The built-in electric field generated by the charge transfer plays a key role in the effective hindrance of photoexcited carrier recombination. The graphene/WSSe heterojunction possesses enhanced optical absorption in the visible light range compared with two freestanding monolayers, implying its potential application in optoelectronic device. Besides, the graphene/WSSe heterojunction displays the n-type Schottky contact characteristics at the equilibrium interlayer distance. Both the interlayer distance and external electric field can be used to modify the Schottky barrier height and contact types of graphene/WSSe heterojunction, and effectively adjust the Dirac cone position of graphene. The research in this paper provides a theoretical basis for the fascinating applications of graphene/WSSe heterojunction in the fields of nanoelectronic and optoelectronic devices.