Identically-sized Co quantum dots (QDs) are constructed on monolayer tungdten disulfide (WS2) forming coupled heterostructures. Topographical images investigated by in situ scanning tunneling microscopy (STM) show a bias-dependent feature. First-principles calculated binding energies combined with the simulated STM images identify that the Co QDs possess a unique magic number, with a tetrahedral Co4 configuration. Numerical differential conductance measured by scanning tunneling spectroscopy (STS) indicates a p-type doping and an Ohmic contact property for the Co4/WS2 system. Mechanism of the novel transport and conduction properties of the coupled heterostructures is further revealed by analyzing the work functions and interfacial interaction. Our findings offer some references for the controlled fabrication of identically-sized zero-dimensional/two-dimensional (0D/2D) heterostructures and propose a feasible strategy for Ohmic interface contact in nanodevices.

中文翻译：

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具有欧姆接触的单层WS2上大小相同的Co量子点

大小相同的Co量子点（QD）构造在单层二硫化钨（WS2）上，形成耦合的异质结构。通过原位扫描隧道显微镜（STM）研究的地形图显示了偏差相关的特征。第一性原理计算出的结合能与模拟的STM图像相结合，确定出Co QD具有独特的幻数，具有四面体Co4构型。通过扫描隧道光谱法（STS）测量的数值差分电导表明Co4 / WS2系统具有p型掺杂和欧姆接触特性。通过分析功函数和界面相互作用，进一步揭示了耦合异质结构的新型传输和传导特性的机理。