二维铁电材料的设计

Two-dimensional (2D) materials with high mobility (graphene, MoS2, phosphorene, etc.) hold the promise to take the place of silicon as the fundamental materials for circuits of a new generation. To enable them non-volatile memory, much research has been devoted to inducing magnetism on them. However, similar to diluted magnetic semiconductors, magnetic 2D materials encounter problems like chemical instability, low magnetic moments, lacking of bandgaps, and low Curie temperature. Those problems are expected to be solved by the ferroelectric 2D materials proposed in this program, note that many functionalized 2D materials that have been fabricated recently may become ferroelectric. By selecting proper chemical functional groups, in this program we will design a number of ferroelectric 2D functionalized materials, and field effect transistors, PN junctions, ferroelectric/multiferroic junctions with multiple resistance states based on them, referring to the concepts from 3D metal oxide heterostructures. They constitute a new family of 2D multifunctional devices thinner than 1nm, which are expected to be directly integrated into future circuits based on 2D materials. The program will be also focused on heterostructures based on 2D materials functionalized by different groups, the polar discontinuity and charge transfer at the interface will be investigated, and the mechanism of 2D ferroelectric tunneling will be studied for enhancing the giant electroresistance. The research in this program is mainly based on first-principles calculations, and will be combined with experiments through collaborations.

高迁移率二维材料（石墨烯，二硫化钼，黑磷等）有望取代目前硅材料成为新一代电路基本材料。为了使其同时拥有非易失性记忆功能，有大量研究试图使其获得磁性。但类似于稀磁半导体，磁性二维材料面临着化学性质的不稳定，饱和强度低，缺少半导体能隙及居里温度低等诸多问题。本项目提出的铁电化二维材料有可能解决以上问题，而近来合成的功能化二维材料中不少就有望能够铁电化。通过合适化学基团的选取，借鉴三维金属氧化物异质结的各种概念，本项目将设计出多种铁电性的功能化二维材料，及以此为基础的场效应管，PN结，拥有多阻态的铁电/多铁隧穿结，构成一个二维多功能新型器件的家族，其厚度在1纳米以内，有望直接集成于未来基于二维材料的电路中。本项目还将关注以不同基团在二维材料上修饰的异质结，将分析界面处的极化不连续和电荷转移，并通过研究二维铁电隧穿机制提高其巨电致电阻。研究方法将以第一性原理计算为主，并将通过合作与实验结合。

高迁移率二维材料（石墨烯，二硫化钼，黑磷等）有望取代目前硅材料成为新一代电路基本材料。为了使其同时拥有非易失性记忆功能，有大量研究试图使其获得磁性。但类似于稀磁半导体，磁性二维材料面临化学性质的不稳定，饱和强度低，缺少半导体能隙及居里温度低诸多问题。本项目提出铁电化二维材料有可能解决以上问题，在该项目支持下主持人目前已预测了十多种铁电性二维材料，将二维铁电体系大为拓展，并以通讯作者在JACS等IF>10的期刊上发表8篇文章。有几种预测体系在随后实验中证实，其中不乏高迁移率半导体，而且居里温度都在室温以上。这些体系中还存在多样的多铁耦合，可以用于信息数据高效的“电写磁读”。