二维Janus结构的PdSSe/石墨烯接触特性的第一性原理探究

First-principles investigation of the contact properties of PdSSe/graphene with two-dimensional Janus structures

Janus结构由于其两侧的原子不同,存在一个内建电场.在本工作中,将具有Janus结构的六角PdSSe与石墨烯复合,构成范德瓦尔斯异质结构.通过基于密度泛函理论的第一性原理计算对其几何结构和电子结构进行了研究.计算中考虑了两种堆叠方式,即Se侧与石墨烯接触和S侧与石墨烯接触.当S侧与石墨烯接触时,体系具有更小的平衡间距和更大的电荷转移,结合能更低.S侧与石墨烯接触时形成了为n型欧姆接触;Se侧与石墨烯接触时形成了势垒极低的n型肖特基接触.最后,讨论了垂直应变对接触特性的影响.通过施加垂直应变,PdSSe/石墨烯的接触类型具有显著的可调性.

The Janus structure has a built-in electric field due to the different atoms on its two sides.In the present work,hexagonal PdSSe with Janus structure is compounded with graphene to form a van der Waals heterostructure.The geometric and electronic structures are investigated by first-principles calculations based on density functional theory.Two types of stacking,Se side and S side in contact with graphene,are considered in the calculations.When the S-side is in contact with graphene,the system has smaller equilibrium spacing and larger charge transfer with lower binding energy.N-type Ohmic contacts are formed when the S-side is in contact with graphene,n-type Schottky contacts with extremely low potential barriers are formed when the Se-side is in contact with graphene.Finally,the effect of vertical strain on the contact properties is discussed.The contact type of PdSSe/graphene is significantly tunable by applying vertical strain.