Vertically Conductive MoS₂ Spiral Pyramid

c-AFM experiments were conducted on CVD-grown MoS₂ spiral pyramid samples and mechanically exfoliated MoS₂ samples, which clearly exhibit the difference for the vertical electrical transport between these two cases. The MoS₂ spiral sample is synthesized via CVD on a SiO₂ substrate. The growth is initiated (nucleated) at a vertically mismatched overlapping of two edges, leading to a screw dislocation having Burgers vector. The growth is then followed by a step-flow growth mode similar to multilayer grapheme. The as-prepared sample is transferred to the copper TEM grid by poly(methyl methacrylate) (PMMA). It was found that the instability is developed at the growing steps/edges and the buried terraces by TEM, which is due to the specific source supply during CVD growth, which may also interfere with the well-defined spiral structures. Most importantly, the feasibility of the helical electrical transport was confirmed through the central threading dislocation in the spiral pyramid for this kind of atomic layer and showed their superior vertical conductance, which may open up various possibilities of interesting applications for this kind of peculiar nanostructures.