基于硼烯的新型纳米器件模型设计与性能调控及其机理研究

Recently, borophene, another novel nano-materials after the discovery of graphene, has been successively prepared in experiments. According to the research status at home and abroad, several critical questions have yet to be known. For instance, it is unknown that which functional characteristics the borophene can display, especially in the electrical properties, and could work well in the fields of electronic devices and nanoelectronics; which methods could be used to increase its features. Tracking the newest experimental results, this project will systematically investigate the electronic transport properties of the newly prepared three types of borophene(i.e., one non-coplanar and two types of coplanar), using the density functional theory combined with non-equilibrium Green's function method. Several factors will be investigated which could influence the electronic structures and transport properties of borophene nanoribbons, such as the both cutting orientations, the width and length size effects, the manipulations of edge-states (i.e., bare, hydrogenated, oxidized, and fluorinated), structural defects and doped impurities. We will investigate the relationships between the electronic transport properties of borophene nanoribbons and several external factors, and design many borophene-based nano-device models owning various functions. We also expect to work out some methods to control the device performances, and the corresponding mechanisms as well. Above all our results will supply some detailed important theoretical basises for further preparation of borophene-based nano-devices in experiments.

最近实验上成功制备出继石墨烯之后又一种“奇特纳米材料”–硼烯。综合国内外研究现状，对于硼烯具体能表现出哪些功能特性，尤其是电学特性，使其能在电子器件或纳米电子学领域大显身手，或者通过哪些量子调控措施来丰富其功能特性，还有诸多关键问题尚未被人们所知。本项目及时跟踪这一最新实验成果，拟采用密度泛函理论结合非平衡格林函数方法，系统研究最新制备出来的三种硼烯的电子输运性质，即褶皱型和两种共面型硼烯。分别研究多种因素对硼烯纳米带的电子结构以及电子输运性质的影响，例如硼烯纳米带的两种裁剪方式、纳米带带宽和长度尺寸效应、边缘态结构调控(如边缘无修饰、加氢饱和、氧化或氟化等)、结构缺陷和杂质掺杂等。探究硼烯纳米带的电子输运性质与多种因素的依赖关系，以期设计出具有多种功能特性的基于硼烯的纳米器件模型，并探寻一些器件性能调控措施及其物理机制，为在实验上进一步制备基于硼烯的纳米器件提供详细的重要理论依据。

近年来，实验上成功制备了一种新的二维材料硼烯，其电子输运性质及在纳米电子学领域的潜在应用等诸多关键问题尚未被人们所知。本项目及时跟踪这一最新实验成果，设计了一些基于硼烯及类硼烯的纳米器件结构，并采用密度泛函理论、非平衡格林函数方法及超导体密度泛函理论研究了它们的电子输运性质和光电性质，探究了其器件性能调控措施，分析了其电子输运机理。主要研究结果如下：1)氢化硼烯B4H4表现出电流限制效应, 在光照下可以产生较大光电流，对蓝光和绿光有较强的光响应; 完全氢化硼烯表现出较强的电各向异性,可实现开关功能; 2) ZrB2单层在低偏压下电子主要沿着其Zr-Zr金属键传输；在高偏压下，表现出明显的电各向异性；ZrB2表现出负微分电阻效应，即使当存在Zr原子空位缺陷时，该特性仍然存在; 3）设计了多种由过渡金属二硫化物侧面异质结构成的纳米器件模型，并研究了它们的自旋输运性质和光电性质，其二极管结构表现出较强的自旋整流效应，扶手椅型器件表现出较强的自旋极化现象，门电极可明显调控其场效应晶体管的电流和整流比率，其对蓝光具有较明显的光电响应，可用于光电探测器和光伏器件；4) 此外，我们基于格林函数表面模型，发展了一种计算二维材料从其块体结构或衬底上剥离的剥离能的高效方法，还研究了MgB2型二硼化物的超导电性和拓扑性质，结果表明包含范德华修正的OptB88-vdW泛函可以给出与实验值较吻合的超导转变温度，为范德华材料的超导电性和拓扑性质研究提供了有用指导。通过该项目的研究，加深了对硼烯及类硼烯结构的电子输运性质认识，了解了其在纳米电子器件和光电器件领域的潜在应用价值，为进一步制备相关原型器件提供了重要理论支撑。