Hu Xuemin, Liu Wenqiang, Yang Jialin, Zhang Shengli, Ye Yuanfeng
School of Material Engineering, Jinling Institute of Technology, Nanjing 211169, China.
MIIT Key Laboratory of Advanced Display Materials and Devices, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Phys Chem Chem Phys. 2021 Nov 17;23(44):25136-25142. doi: 10.1039/d1cp03850h.
The electrical contacts at the van der Waals (vdW) interface between two-dimensional (2D) semiconductors and metal electrodes could dramatically affect the device performance. Herein, we construct a series of graphene (Gr)/XC (X = P, As, Sb, and Bi) vdW heterostructures, in which XC monolayers have aroused considerable attention recently as an emerging class of 2D semiconductors. The electronic structures and contact properties of Gr/XC vdW heterostructures are investigated systematically using first-principles calculations. The band structures indicate that both Gr/PC and Gr/AsC heterostructures form n-type Schottky contacts with Schottky barrier heights (SBHs) of 0.01 eV and 0.43 eV, respectively, while both Gr/SbC and Gr/BiC heterostructures preferably form Ohmic contacts. The different X atoms result in different work functions, electron flows, charge distributions and orientations of the dipole moment in Gr/XC heterostructures. Moreover, the tunneling probabilities increase with the increasing atom radius of X from P to Bi, indicating the most improved current and smaller contact resistance at the interfaces of Gr/BiC compared to Gr/PC, Gr/AsC and Gr/SbC heterostructures. Our work could provide meaningful information for designing high-performance nanoelectronic devices based on Gr/XC heterostructures.
二维（2D）半导体与金属电极之间范德华（vdW）界面处的电接触会显著影响器件性能。在此，我们构建了一系列石墨烯（Gr）/XC（X = P、As、Sb和Bi）范德华异质结构，其中XC单层作为一类新兴的2D半导体最近引起了相当大的关注。使用第一性原理计算系统地研究了Gr/XC范德华异质结构的电子结构和接触特性。能带结构表明，Gr/PC和Gr/AsC异质结构均形成n型肖特基接触，肖特基势垒高度（SBH）分别为0.01 eV和0.43 eV，而Gr/SbC和Gr/BiC异质结构则更倾向于形成欧姆接触。不同的X原子导致Gr/XC异质结构中功函数、电子流、电荷分布和偶极矩方向不同。此外，隧穿概率随着X原子半径从P到Bi的增加而增加，这表明与Gr/PC、Gr/AsC和Gr/SbC异质结构相比，Gr/BiC界面处的电流改善最大且接触电阻更小。我们的工作可为基于Gr/XC异质结构设计高性能纳米电子器件提供有意义的信息。
