Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
Phys Rev Lett. 2019 Aug 16;123(7):076801. doi: 10.1103/PhysRevLett.123.076801.
Structural defects in 2D materials offer an effective way to engineer new material functionalities beyond conventional doping. We report on the direct experimental correlation of the atomic and electronic structure of a sulfur vacancy in monolayer WS_{2} by a combination of CO-tip noncontact atomic force microscopy and scanning tunneling microscopy. Sulfur vacancies, which are absent in as-grown samples, were deliberately created by annealing in vacuum. Two energetically narrow unoccupied defect states followed by vibronic sidebands provide a unique fingerprint of this defect. Direct imaging of the defect orbitals, together with ab initio GW calculations, reveal that the large splitting of 252±4 meV between these defect states is induced by spin-orbit coupling.
二维材料中的结构缺陷为超越传统掺杂的新型材料功能工程提供了有效途径。我们通过 CO 针尖非接触原子力显微镜和扫描隧道显微镜的组合，直接实验关联了单层 WS_{2}中硫空位的原子和电子结构。在真空退火中故意产生了在原始生长样品中不存在的硫空位。两个能量狭窄的未占据缺陷态，后面跟着振动态边带，为该缺陷提供了独特的指纹。缺陷轨道的直接成像以及 ab initio GW 计算表明，这些缺陷态之间 252±4 毫电子伏特的大分裂是由自旋轨道耦合引起的。
