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王学森:Self-assembled Bi and Sb few-atomic-layer nanostructures(时间9.25)
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报告人:王学森 新加坡国立大学物理系副教授

报告时间:9月25日上午9:00

报告地点:物理楼B304会议室

主办单位:光伏材料重点实验室

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  报告摘要:Few-atomic-layer nanostructures of Bi and Sb are 2D semiconductors or semimetals, which potentially can be excellent thermoelectric materials, topological insulators, or useful in energy storage systems.  On graphite and MoS2 with physical vapor deposition, we observed the self-assembly of several types of Sb and Bi nanostructures, including ultrathin films and nanobelts. Systematic STM-based investigation reveals the crucial roles of diffusion and dissociation of deposited species, as well as the surface stress of the nanostructures in determining the types of nanostructures observed.  In particular, at thickness < 8 ML, Bi and Sb ultrathin films appear to start as compressed highly isotropic square-phase nuclei.  In a later growth stage, the nuclei undergo a symmetry-breaking transition to form nanobelts as strain relaxation occurs.  Their lattice parameters deviate significantly from that of 3D bulk Bi or Sb crystals, which may generate change in the electronic structures.  Based on our understandings in the nucleation, growth and relaxation mechanisms, certain morphological control of Sb and Bi nanostructures self-assembled on inert substrates has been accomplished, making it possible to fabricate the few-atomic-layer nanostructures of Bi and Sb with certain desirable electronic properties.

  王学森, 1982年毕业于复旦大学物理系,1990年在马里兰大学获得物理学博士学位,先后在香港科技大学、新加坡国立大学任助理教授,2007年至今在加坡国立大学任助理教授、副教授。主要研究领域包括表面科学、薄膜、纳米科学。主要成果有:用STM测定硅 (111)表面上原子台阶的相互作用及对表面稳定性的影响,并利用吸附改变表面上原子台阶的尺寸与统计分布;确定了Ge/GaAs (001)界面形成时的原子结构演化及Ge在GaAs (001)上的SK生长模式;STM测定离子轰击GaAs (001)表面产生的缺陷构造、表面粗糙过程 以及这些缺陷对Ge在GaAs (001)上沉积生长的影响;在硅 (001)表面成功制备出晶态外延氮化硅薄膜,并分析了表面及界面的原子结构;分析在石墨、硫化钼及氮化硅薄膜上自组生长的Si、Ge、Al、Sb、Bi、Mn、MnSb等团簇、纳米晶粒及纳米线(链)的形貌与表面原子结构随颗粒尺寸的变化;从锑、铋薄膜及纳米结构中寻找单元素拓扑绝缘体。


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