Line Defects in Molybdenum Disulfide Layers

TL;DR

This paper investigates intrinsic line defects in MoS2 layers, revealing their atomic structure and electronic effects, which could explain the low electron mobility observed in single-layer MoS2.

Contribution

It provides experimental atomic-resolution images and quantum-mechanical modeling of line defects in MoS2, highlighting their electronic states and structural stability.

Findings

Line defects are observed experimentally using TEM.

Defects introduce new electronic states within the band gap.

Stable defect structures include metallic Mo-Mo bonds and bridging S atoms.

Abstract

Layered molecular materials and especially MoS2 are already accepted as promising candidates for nanoelectronics. In contrast to the bulk material, the observed electron mobility in single-layer MoS2 is unexpectedly low. Here we reveal the occurrence of intrinsic defects in MoS2 layers, known as inversion domains, where the layer changes its direction through a line defect. The line defects are observed experimentally by atomic resolution TEM. The structures were modeled and the stability and electronic properties of the defects were calculated using quantum-mechanical calculations based on the Density-Functional Tight-Binding method. The results of these calculations indicate the occurrence of new states within the band gap of the semiconducting MoS2. The most stable non-stoichiometric defect structures are observed experimentally, one of which contains metallic Mo-Mo bonds and another one bridging S atoms.