Grain boundary-mediated nanopores in molybdenum disulfide grown by chemical vapor deposition

Abstract

Molybdenum disulfide (MoS2) is a particularly interesting member of the family of two-dimensional (2D)materials due to its semiconducting and tunable electronic properties. Currently, the most reliablemethod for obtaining high-quality industrial scale amounts of 2D materials is chemical vapor deposition(CVD), which results in polycrystalline samples. As grain boundaries (GBs) are intrinsic defect lines withinCVD-grown 2D materials, their atomic structure is of paramount importance. Here, through atomic-scaleanalysis of micrometer-long GBs, we show that covalently bound boundaries in 2D MoS2tend to bedecorated by nanopores. Such boundaries occur when differently oriented MoS2grains merge duringgrowth, whereas the overlap of grains leads to boundaries with bilayer areas. Our results suggest that thenanopore formation is related to stress release in areas with a high concentration of dislocation cores atthe grain boundaries, and that the interlayer interaction leads to intrinsic rippling at the overlap regions.This provides insights for the controlled fabrication of large-scale MoS2samples with desired structuralproperties for applications.