含硼/磷拟卤素及磁性超卤素调控硅烯电磁性质的微观机理研究

Silicene has the Dirac electronic structure which is similar to that of graphene. In this case, the quantum Holzer effect of graphene can also be found in silicene. Furthermore, it is compatibility with the electron device based on silicon materials. However, the small band gap of silicene limit its application in nano electron device. This project concretely aims at the key scientific problems regarding the improvement of the band gap and magnetic properties of silicene and maintaining its high carrier mobility. The main research contents are as following: Using the density functional theory combined with the CALYPSO global structure prediction technique, we try to construct the ground state structure model of the silicene which is modified by different contents of B and P, pseudohalogens BO2 and PO3, as well as magnetic superhalogens Fe(BO2)4 and Fe(PO3)4. Based on the binding pattern, energy band, carrier mobility and electron spin density, the intrinsic physical mechanism of making silicene exhibit more excellent properties will be investigated. In addition, we will discuss whether the magnetic properties of silicene can be greatly enhanced by adsorption of magnetic superhalogen, and the transformation between non-magnetic and ferromagnetic states could be controlled. This research will not only establish the theory to describe the regulation of electronic and magnetic properties of silicene, but also provide theoretical support for application of silicene in nano electronic devices. It has important scientific significance in the development of the cross-science between atomic and molecular physics and material science.

硅烯具有类石墨烯的狄拉克型电子结构，可实现在石墨烯中发现的量子效应，并能与硅基半导体材料兼容。然而，硅烯的带隙较小，这限制了其在纳米电子器件方面的应用。本项目将研究调控硅烯带隙及磁性并保持其高载流子迁移率这一重要科学问题。研究内容包括：结合CALYPSO全局结构预测技术及密度泛函理论，构建硼磷元素、拟卤素BO2和PO3、以及磁性超卤素 Fe(BO2)4和Fe(PO3)4修饰硅烯表面的基态结构模型。从修饰物质与硅烯的结合方式、能带结构、载流子迁移率和电子自旋密度等角度探讨使硅烯表现出更优异特性的物理微观机理。通过磁性超卤素修饰调控硅烯的磁性，研究其非磁状态与铁磁状态的转换。本项目将发展一种能描述硅烯电磁性质调控的理论方法，为把硅烯制备成硅基纳米电子器件提供理论依据，这对于推动原子分子物理和材料科学的交叉发展具有重要意义。

硅烯具有与石墨烯类似的狄拉克型电子结构，可实现石墨烯中发现的量子效应，并且硅烯与目前最常用的硅基电子器件有良好的兼容性。然而，硅烯的带隙非常小，这阻碍其在纳米电子器件方面的应用。本项目针对调控硅烯带隙及磁性并保持高载流子迁移率这一关键科学问题展开研究。结合CALYPSO全局结构预测技术及密度泛函理论，设计探究具有强氧化性、强磁性的超卤素，并用其调控硅烯电子性质与磁性。从修饰物质与硅烯的结合方式、能带结构、载流子迁移率和电子自旋密度等角度探讨使硅烯表现出更优异特性的微观机理。结果成功设计出多种以拟卤素（如BO2）为配体的新型铁基磁性超卤素，并创新性地将拟卤素配体磁性超卤素推广到多核，大大增强超卤素磁性。探讨影响其超卤素特性的机理，发现主要因素为阴离子中额外电子分布以及成键情况。对不同数目氧原子、硼原子及超卤素调控硅烯特性进行了系统研究。结果表明不同数目的氧原子吸附可使硅烯成为直接或者间接带隙的半导体。基于电子有效质量计算载流子迁移率，发现超卤素吸附后硅烯载流子迁移率仍保持在高于石墨烯水平。然而这些原子、超卤素的吸附对硅烯的磁性则基本没有贡献。. 所取得研究成果以论文的形式发表在国际SCI杂志上，共计8篇SCI，同时授权国家发明专利一项。本项目先后获“陕西省科学技术奖”以及“陕西省高等学校科学技术奖”。本项目为硅烯制备成硅基纳米电子器件提供理论依据，为推动原子分子物理和材料科学的交叉发展做出一定贡献。