hBN封装二维材料的物性及屏蔽效应的理论研究

Two-dimensional (2D) semiconductor device with high quality is one of researching hotspots currently, and its performance can be substantially enhanced via hBN-encapsulation. The encapsulation of 2D materials with hBN enables its surface to be sealed, not only can protect them from environmental interactions to obtain clean interfaces, but also yields improved physical properties due to the interfacial effects. Based on first-principles calculations in the framework of density functional theory, combining with semiclassical boltzmann theory, we plan to investigate the physical properties of hBN-encapsulated 2D materials and relevant shielding effects. The concrete contents are as follows: 1. The structural stability, interfacial effect, electronic structure, magnetism, optical characteristic and transport property of different 2D material(such as graphene, MoS2, phosphorene) encapsulated with hBN; 2. The effects of various outside disruptive factors (such as electric field, strain ,molecular impurity, humidity, temperature variation) on the long-term stability and physical properties of the different 2D materials with and without hBN-encapsulation; 3. The rule summary, quantitative expression and theoretical prediction on the shielding effects in hBN-encapsulated layered heterostructures. This project aims to reveal the reasons responsible for improved device performance of hBN-encapsulated 2D materials and explore various limiting cases of the shielding effects in different 2D material under diverse influences, and then develop an instructive encapsulation theory. In brief, we intend to find outstanding 2D materials and design practical encapsulation schemes, contributing to realizing high quality 2D semiconductor-based devices in experiments.

高性能二维半导体器件是当前研究的一大热点，对二维材料进行“封装”是提升其性能的有效方法。封装二维材料不仅能为其提供物理隔离从而避免外界的污染和干扰，更可以利用二维材料层间的界面效应改进其物性。本项目拟采用第一性原理计算方法和半经典玻尔兹曼理论相结合，研究hBN封装型二维材料的物性和封装效应。具体研究内容如下：1. hBN封装不同二维材料（石墨烯、二硫化钼、磷烯等）的结构稳定性、界面效应、电磁特性、光学性质和输运性能；2. 外界环境干扰（电场、应力、小分子吸附、湿度、温度等）对hBN封装前后二维材料相关物性的影响，探究是否存在屏蔽效应；3. 屏蔽效应的规律总结、量化分析以及理论预测。该研究旨在探究hBN对二维材料的封装效果，归纳屏蔽效应的作用范畴，揭示hBN封装提升二维材料性能的物理化学机制，奠定“封装技术”的理论基础。并设计出更好的封装方案，从而为实验上实现高性能二维半导体器件提供指导。

本项目基于宽禁带半导体二维结构（BN、GaN和SiC）异质结封装模型，着眼于二维材料的"新大陆"-范德华异质结，致力于二维材料应用于光催化、新能源材料与器件的设计和开发研究。项目采用密度泛函理论与玻尔兹曼输运理论相结合的方法，从界面相互作用研究了宽禁带半导体二维结构封装石墨烯、磷烯、g-C3N4和PtSe2等二维半导体材料的稳定性、界面特性以及屏蔽效应，探究不同环境因素（电场、应力、分子吸附等）封装体系（范德华异质结）的电子结构、电荷空间分布和载流子迁移率，阐明了界面作用与屏蔽效应的关系，归纳并分析总结了外在环境因素的种类、强弱与屏蔽效果的联系，为封装屏蔽效应的应用提供模型方案和理论基础。本研究实现了高效可行的复合多功能材料，从结构构建、性能调控、界面效应和协同作用等多层面开展研究，阐明构效关系及机理，为推动二维材料在光催化科学发展、范德华异质结光催化剂在太阳能产氢的实际应用提供重要理论指导和数据模型支撑。