硅烯的原位制备、电子结构和超导电性的角分辨光电子能谱研究

Silicene represents a monolayer silicon that has attracted much recent attention.It is expected to share similar electronic structure with the graphene. But the warped non-coplanar structure may induce stronger spin-orbital coupling that is likely to open a larger gap at the Dirac point, thus making the quantum spin Hall effect possible. Silicene is also predicted to be a candidate of a two-dimensional topological insulator, where many novel quantum phenomena, such as anomalous quantum Hall effect, valley-polarized metal phase, can be realized. In addition, theoretical calculations and experimental indications show that high temperature superconductivity may be realized in doped silicene. Since silicene is easy to be integrated into the current mainstream silicon semiconductor technology, it will show promising applications in industry. However, the study of silicene is still in its early stage, and many important issues meed to be addressed. We propose to make a systematic investigation on the preparation, electronic and spin structure and superconductivity, by using our VUV laser- based spin- and angle- resolved photoemission spectroscopy system combined with in situ molecule beam epitaxy (MBE) growth system. We will prepare silicene with different crystal structure under various preparation conditions. We will study the electronic structures and spin structures of these silicene samples. We will investigate layer-dependent electronic structure of silicene. We will try various ways to dope silicene, to investigate its electronic evolution with doping and the possibility of superconductivity. Through these systematic study, we hope to gain deep understanding on the preparation, electronic and spin structure, and properties and superconductivity of silicene.

作为单层的硅材料--硅烯具备与石墨烯类似的狄拉克型电子结构，非共面结构使得其具有更强的自旋轨道耦合，可能在狄拉克点打开更大的能隙，因此可实现可观测的量子自旋霍尔效应；还被认为是二维拓扑绝缘体，可能出现量子反常霍尔态、谷极化金属态拓扑相变等新奇量子现象。另外通过掺杂等手段，有可能在硅烯上实现超导电性。应用上，硅烯与目前的硅技术相融合，将有利于大规模集成电路的生产。但是硅烯研究刚刚起步，很多问题需要解决。我们将采用我们自主研制的国际领先的深紫外激光角分辨光电子能谱以及世界首台的自旋分辨激光角分辨光电子能谱仪开展如下内容：1.采用不同的生长条件，生长不同结构的硅烯材料，开展不同结构材料的电子结构研究以及自旋电子结构研究；2生长不同层数的硅烯材料，开展层数对电子结构的影响的研究；3.我们将尝试不同方法掺杂硅烯，开展掺杂对电子结构以及超导电性的研究。通过我们的深入研究，来加深对硅烯的理解。

作为单层的硅材料--硅烯具备与石墨烯类似的狄拉克型电子结构，可能实现可观测的量子自旋霍尔效应；还被认为是二维拓扑绝缘体，可能出现量子反常霍尔态、谷极化金属态拓扑相变等新奇量子现象。另外通过掺杂等手段，有可能在硅烯上实现超导电性。我们采用不同的生长条件，生长除了不同结构的硅烯材料，并采用我们自主研制的国际领先的深紫外激光角分辨光电子能谱对不同结构的硅烯的电子结构开展研究。通过对Ag（111）上生长的3X3重构的硅烯进行角分辨光电子能谱测量，我们发现在Ag(111)第一布里渊区边界上存在六对狄拉克锥，这与预期的在原始1X1硅烯的K点存在狄拉克锥的模型形成了鲜明的对比。我们的分析表明这种不寻常的狄拉克锥结构并不是单独来自于原始的硅而是源于硅烯与Ag（111）衬底相互作用的结果。 我们的研究确定了一种独特的由两者相互作用而产生的狄拉克锥结构。单层硅烯/Ag(111)体系中狄拉克锥的发现为研究二维硅材料中不同寻常的量子现象及应用提供了一个独特的平台。另外我们还对√3 x√3 结构进行了电子结构研究，取得了重要的结果。