高迁移率的二维原子晶体的能带调控，器件模拟，与多体效应

With the rise of graphene,research in electronic nanomaterials, historically dominated by studies of nanocrystals/fullerenes and nanowires/.nanotubes, now incorporates a growing focus on two-deminsional nanostructures.Graphene and other 2D nanostructures are the most active field nowadays.Such materials have practical appeal because their two-dimensional geometries facilitate integration into devices, with realistic pathways to manufacturing. Graphene, silicene, and germanene have extremely high carrier mobility, suggestive of high device switch speed.However, their zero band gap prevents them from fabricating effective field effect transistor (FET) operating at room temperature. Opening a tunable band gap is critical for device application of them. We will investigate the possibility of opeing their band gap by adsorption of atoms and molecules on one side and simulate their transport as FET. We will try to transform silicene and germanenen into magnetic material via single-side functionalzation or generating holes. It has been well established that the many-body effects (self-energy correction and electron-hole interaction) on the electronic structure and optical absorption are greatly enhanced in low-dimensional system owing to the reduced screening and geometrical confinement.We will study the quasiparticle energy band and excitonic effects in silicene and germanene.

随着石墨烯的出现，纳米材料的研究正从以零维的纳米晶粒（富勒烯），一维的纳米线/纳米管为主，注意力越来越转向二维纳米材料。石墨烯，硅烯，锗烯具有远高出块材硅的载流子迁移率，可制成快速切换的电子装置。同时它们也易于集成到装置中。但纯的石墨烯，硅烯，锗烯能隙为零，不适合做有效的室温场效应管。因而打开和调控它们的能隙并维持高迁移率是其走向器件应用的关键。我们考虑用第一性原理方法探索通过原子和分子单面吸附在双层，多层石墨烯以及单层硅烯锗烯上，实现能隙的打开和连续调节。以打开能隙的石墨烯，硅烯，锗烯作为沟道，理论模拟出相应的单门场效应管器件。通过单面修饰和挖洞，把硅烯，锗烯改造为磁性材料。二维单层结构的一个显著的特点是由于减小维度导致减小的屏蔽，使得准粒子的能带修正和激子效应都比三维块材明显增强。我们计划研究硅烯和锗烯准粒子能带和激子效应。

二维材料由于超薄带来的门的极好的控制性能以及表面光滑带来的界面处不存在陷阱，是下一代晶体管的极其具有竞争力的沟道材料。二维的狄拉克材料石墨烯硅烯还具有高的载流子迁移率，有做高表现器件的潜力，然而零的能隙限制了它们在逻辑器件中的应用。除了通过单面吸附打开多层石墨烯和单层硅烯的能隙，我们通过第一性原理计算还发现把石墨烯硅烯组成异质结，也可以打开一个大的输运能隙，相应的器件有很高的开关比。考虑自旋轨道耦合，铋烷和锑烷由狄拉克材料变为最大能隙拓扑绝缘体。我们在材料科学顶级综述杂志上撰写了迄今为止最为全面介绍硅烯的长篇综述文章。二维半导体可以避免狄拉克材料无能隙的问题。但二维材料缺乏有效的替代掺杂手段，通常需要与金属接触直接接触。而肖特基势垒通常会存在半导体金属的界面，它会减小载流子的注入效率，进而降低器件的表现。形成低电阻的半导体金属接触是巨大的挑战。我们发展了系统的研究晶体管位型下金属半导体界面的方法，利用这套方法研究了石墨炔，MoS2, WSe2， MoSe2, 磷烯与金属的界面，确定了其中的肖特基势垒。我们研究了亚10-nm的MoS2晶体管的表演极限，发现它在亚10-nm 也可以有很好的表现，研究结果得到最近Science上工作的证实。有3篇论文进入ESI高被引用论文，1篇论文进入Advanced Electronic Materials 杂志热点论文。