新型石墨烯与类石墨烯横向异质结界面效应的第一性原理研究

With the rise of graphene and graphene-like as two-dimensional semiconductor materials, most studies have focused on the novel lateral heterostructures composed of graphene and graphene-like in nano science, materials science, and novel semiconductor device research. However, the interface effect in the semiconductor heterojunction would decrease the device performance due to scattering the carrier and reducing the electron mobility. In this project, the electronic structure and tranport properties of lateral Graphene/h-BN and MoS2/WS2 heterojunctions with structure relaxation, dislocation and atomic diffusion, will be investigated by an ab initio scheme which combines nonequilibrium Green's approach with density function theory. Firstly, the structure of lateral junctions with such interface effect will be defined, then the impact of interface effect on heterojunction band offset and modulation of quantum transport processes will be explored. In order to achieve improved devices, the nano-electronic devices based on lateral heterojunctions are optimized. This project will not only enrich the knowledge of electronic structures lateral heterojunction composed of graphene and graphene-like, but also provide theoretical guidance and design proposal for nano-electronic devices based on lateral heterojunctions.

随着石墨烯和类石墨烯二维半导体材料的兴起，新型二维半导体横向异质结正在成为国际前端纳米科学、材料科学以及新型半导体器件研究中的焦点。然而，在半导体异质结中所存在的界面效应对载流子的散射等作用降低了电子迁移率，致使半导体器件性能下降。本项目拟采用密度泛函理论和非平衡格林函数相结合的第一性原理计算方法，基于Graphene/h-BN和MoS2/WS2横向异质结，研究结构弛豫、位错和原子间扩散三种界面效应对横向异质结电子结构和输运性质的影响，确定三种界面效应下异质结的微观结构，揭示界面微观几何结构与异质结带阶之间的内在联系，改进具有界面效应的横向异质结的器件模型，提高其器件性能，并阐明界面效应对量子输运过程进行调制的物理机制。本项目的开展不仅丰富了石墨烯与类石墨烯横向异质结电子结构的研究，也将为其在纳米光电子元器件中的应用和发展提供理论指导和量子设计方案。

本项目致力于二维石墨烯与类石墨烯异质结界面效应的研究，包括异质结的微观几何结构及其界面效应的理论分析，探索并设计基于二维异质结纳米电子器件的模型。经过三年的研究，本项目很好的完成了预定的任务，在如下四个方面取得了重要成果：（1）基于BN掺杂的zigzag石墨烯纳米带构建了横向异质结，实现自旋极化率为100%的电流，并研究了界面效应（连接方式）对量子输运的调控；（2）构建ZGNRs/(BN)n/ZGNRs横向异质结，发现其具有热电效应，ZBNNRs所引起的势垒部分是异质结产生热电效应的关键因素；（3）构建ZBNNRs/ZGNRs/BNNRs纵向异质结光电器件，研究界面效应（层间距、堆叠方式、层间滑移）对光电流、自旋流的调控机理；（4）针对单层三磷化铟与石墨烯、六角氮化硼异质结界面效应，构建物理模型，揭示产生界面效应的主要因素，为纳米器件电极材料的选取及设计提供了理论依据和指导。迄今已发表相关论文7篇，受项目资助的论文发表在研究结果发表在Carbon、J. Phys. D: Appl. Phys. 、Nanoscale、PCCP等国际著名期刊上。