超高真空条件下分子束外延生长的单层二维原子晶体材料的研究进展

二维原子晶体材料具有与石墨烯相似的晶格结构和物理性质,为纳米尺度器件的科学研究提供了广阔的平台.研究这些二维原子晶体材料,一方面有望弥补石墨烯零能隙的不足;另一方面继续发掘它们的特殊性质,有望拓宽二维原子晶体材料的应用领域.本文综述了近几年在超高真空条件下利用分子束外延生长技术制备的各种类石墨烯单层二维原子晶体材料,其中包括单元素二维原子晶体材料(硅烯、锗烯、锡烯、硼烯、铪烯、磷烯、锑烯、铋烯)和双元素二维原子晶体材料(六方氮化硼、过渡金属二硫化物、硒化铜、碲化银等).通过扫描隧道显微镜、低能电子衍射等实验手段并结合第一性原理计算,对二维原子晶体材料的原子结构、能带结构、电学特性等方面进行了介绍.这些二维原子晶体材料所展现出的优异的物理特性,使其在未来电学器件方面具有广阔的应用前景.最后总结了单层二维原子晶体材料领域可能面临的问题,同时对二维原子晶体材料的研究方向进行了展望.

Research progress of monolayer two-dimensional atomic crystal materials grown by molecular beam epitaxy in ultra-high vacuum conditions

Two-dimensional atomic crystal materials have similar lattice structures and physical properties to graphene,providing a broad platform for the scientific research of nanoscaled devices.The emergence of twodimensional materials presents the new hope of science and industry.As is well known,graphene is the most widely studied two-dimensional(2D)material in recent ten years.Its unique atomic structure and electronic band structure make it have novel physical and chemical properties and broad applications in electronic devices,optical devices,biosensors,solar cell,and lithium ion battery.In recent years,graphene-like single-layered 2D materials have attracted much attention.Researches of these 2D atomic crystal materials and their physical properties,on the one hand,are expected to make up for the lack of band gap in graphene,and on the other hand,continue to explore their unique properties,expand the application of 2D atomic crystal materials.Among all the preparation methods of single-layered 2D atomic crystal materials,the molecular beam epitaxy(MBE)is considered to be the most competitive method.The manufacturing process of MBE is usually carried out under ultra-high vacuum condition,which ensures the cleanness of the 2D material surface.At the same time,the solid growth substrate needed for epitaxial growth can be used as a carrier to support and stabilize the growth of 2D materials.In this review,we summarize many single-layered 2D materials prepared by MBE under ultra-high vacuum conditions in recent years,including monatomic 2D atomic crystal materials(silicene,germanene,stanene,hafnene,borophene,phosphorene,bismuthene,antimonene)and binary atomic crystal materials(hexagonal boron nitride,transition metal dichalcogenides,copper selenide,silver telluride).In addition,by scanning tunneling microscopy(STM),low-energy electron diffraction(LEED)and first-principles calculations,we investigate the atomic structures,energy gap modulations,and electrical properties of 2D materials.These 2D atomic crystal materials exhibit the excellent physical properties,which will make them have broad application prospects in future electronic devices.Finally,we summarize the problems faced by the further development of 2D materials and suggest several potential development directions.