氢化对硅烯及硅烯纳米条带电子输运性质的调制

Silicene, one of graphene-like materials, has excellent physical properties (such as high carrier mobility, quantum spin Hall effect, etc) and is one of the ideal materials for the preparation of micro-nano electronic devices. Recent experiments have shown that it is possible to grow Silicene on Ag(110) and Ag(111) substrates. This has attracted much attention because of the compatibility of these structures and processes with conventional Si-CMOS technology. In order to improve the value of the practical application of the Silicene, the modulations of its electronic transport properties is critical. As the electron states of Silicene near the Fermi level are mainly from the contribution of the π-electron, surface hydrogenation would be an effective mean to modulate the electronic structure and transport properties. However, there is less research about the modulations of the charged transport and spin transport properties by means of ordered hydrogenation. This project intends to combine the first-principles method and non-equilibrium Green function method to study the properties of the charged transport and spin transport of Silicene and Silicene nanoribbons and how the work function is dependent on the concentration of the orderly partition hydrogenation, modified location and the variation of the transmission direction. We will put forward effective programs to modulate the properties of Silicene's charged transport and spin transport and hope to provide a theoretical basis for the practical application of Silicene micro-nano electronic devices.

作为重要的类石墨烯材料，硅烯具有高载流子迁移率、量子自旋霍尔效应等优异的物理性质，以及结构和制备工艺与传统硅工艺匹配的优点，是制备微纳电子器件的理想材料之一。最近硅烯在Ag(111)和Ag(110)衬底上的成功制备引起了人们的极大关注。对其电子输运性质进行可控的调制是硅烯器件化应用的基础。由于硅烯费米能级附近的电子态主要来自π电子的贡献，表面氢化是一种调制硅烯电子结构和输运性质的有效手段，然而，目前尚无有序氢化对硅烯和硅烯纳米条带电输运和自旋输运性质以及功函数调制的相关研究。本项目拟采用第一性原理与非平衡格林函数相结合的方法研究硅烯和硅烯纳米条带电子输运和自旋输运性质以及功函数依赖于有序分区氢化的浓度、修饰位置以及传输方向的变化规律，解释相关的物理机制，并建立调制硅烯电子输运和自旋输运的有效方案，为硅烯在微纳电子器件中的实际应用提供理论基础。

作为重要的类石墨烯二维材料，硅烯具有高载流子迁移率、量子自旋霍尔效应等优异的物理性质，以及结构和制备工艺与传统硅工艺匹配的优点，是制备微纳电子器件的理想材料之一。最近硅烯和几种类硅烯二维材料的成功制备引起了人们的极大关注，对其电子结构和输运特征进行可控的调制是其器件化应用的基础。我们对硅烯和类硅烯二维体系（例如单层BN、C2N、MoS2、HgTe、Graphyne、Phosphorene等）的电子结构、电输运性质、磁态调制、热输运、热电效应等进行系统研究，结果如下：（1）氢化构型和界面对硅烯/硅烷超晶格的磁性产生了显著的影响，两种不同界面稳定构型基态特征分别表现为反铁磁和无磁性的半导体，体系的磁矩随着硅烯宽度的增加单调增大直至趋于饱和；（2）在硅烯和h-BN的四种不同界面耦合效应下，硅烯的热导率随着长度的指数幂单调增加，并且可以通过增加界面耦合强度来进一步增大幂指数；（3）通过H/F化学修饰过渡金属掺杂的单层氮化硼纳米片可以实现其自旋态由开到关、由高到低的逻辑转换：H修饰Fe-BN的系统自旋态由原来的自旋开（S=5/2）转变成自旋关（S=0）；H修饰的Mn-BN系统和F修饰的Co-BN系统的自旋态从原来的高自旋（S=2）变成了低自旋（S=1/2）；（4）空位掺杂和施加应力是一种协同调控磷烯磁态的有效手段；（5）施加应变使单层HgTe和HgSe从常规绝缘体转变为拓扑绝缘体，并且可以调制其带隙；（6）单层MoS2的热导率对尺寸和粗糙度不敏感，而石墨烯正好相反；（7）单层C2N的平面外振动的声学声子和光学声子共同主导着它的晶格热导，导致C2N晶格热导几乎要比石墨烯的热导低两个数量级；（8）gamma-graphyne纳米带相对于graphene纳米带具有更为优异的热电性能，它的热电品质因子提高了3～13倍。这些结果为基于硅烯和类硅烯的纳米电子器件设计提供了有益的理论指导。