Atomic Electrostatic Maps of Point Defects in MoS₂

Abstract

In this study, we use differential phase contrast images obtained by scanning transmission electron microscopy combined with computer simulations to map the atomic electrostatic fields of MoS2 monolayers and investigate the effect of sulfur monovacancies and divancancies on the atomic electric field and total charge distribution. A significant redistribution of the electric field in the regions containing defects is observed, with a progressive decrease in the strength of the projected electric field for each sulfur atom removed from its position. The electric field strength at the sulfur monovacancy sites is reduced by approximately 50% and nearly vanishes at the divacancy sites, where it drops to around 15% of the original value, demonstrating the tendency of these defects to attract positively charged ions or particles. In addition, the absence of the sulfur atoms leads to an inversion in the polarity of the total charge distribution in these regions.

Mapping 1D Confined Electromagnetic Edge States in 2D Monolayer Semiconducting MoS2 Using 4D-STEM

“…However, a segmented detector does not record the bright field disk directly but interprets a CoM shift from quadrant signal differences, meaning it is less sensitive to intensity redistribution within the quadrant and can be affected by the orientation between detector segments and field vector. There are various reports on electric field and charge density measurements in perovskite (SrTiO 3 , DyScO 3 , BiFeO 3 ) and GaN where the electric field drops to a minimum at the center of an atom position, which helps to locate and differentiate light elements. − There are also studies on 2D materials including graphene, MoS 2 , ,, and WS 2 with some interesting electric field states and magnitude increases observed at the monolayer/bilayer step edge in graphene. However, more work is needed to image periodic uniform edge terminations in 2D crystals to fully understand the electric field distributions and intensities measured by 4D-STEM.…”

“…There are various reports on electric field and charge density measurements in perovskite (SrTiO 3 , DyScO 3 , BiFeO 3 ) and GaN where the electric field drops to a minimum at the center of an atom position, which helps to locate and differentiate light elements. 18−21 There are also studies on 2D materials including graphene, 22 MoS 2 , 14,23,24 and WS 2 25 with some interesting electric field states and magnitude increases observed at the monolayer/bilayer step edge in graphene. However, more work is needed to image periodic uniform edge terminations in 2D crystals to fully understand the electric field distributions and intensities measured by 4D-STEM.…”

Unraveling Intertwined Impacts between the Lattice Vacancy and Substrate on Photonic Quasiparticles in Monolayer MoS2

“…To quantify [V] at different stages and accurately analyze the effect of defect engineering, we employed aberration-corrected STEM to examine the lattice conditions and made statistics on [V] over multiple areas and samples. − At first, the samples were prepared using a wet-transfer method (see Methods for details) and transferred onto STEM grids (Figure a). Figure b shows the schematic atomic structures for a 2H-MoS 2 monolayer viewed from the basal plane and cross-section, where the blue and yellow balls represent the Mo and S atoms, respectively.…”

Origin of contact polarity at metal-2D transition metal dichalcogenide interfaces

“…Proponents of this argument have generally focused on sulfur vacancy (vac S ) defects [15][16][17][18][19] , and indeed, chalcogen vacancies are found to have the lowest formation energy in TMDCs for typical growth conditions 45,51 . S vacancies have also been observed in scanning tunneling microscopy (STM) and scanning transmission electron microscopy (STEM) images of bare 58,59 and Au(111)-supported 60 monolayer MoS 2 .…”