Coupling Distinct Defect Species In 2D Crystals

What Has Been Achieved

A new type of strong coupling between isoelectronic substitutional dopants (Mo dopants) and common lattice defects (sulfur vacancies) has been identified in WS2 by their ~80% probability of co-localization using aberration-corrected scanning transmission electron microscopy. The coupling mechanism and the Mo dopant’s ability to facilitate the charging of sulfur vacancies is identified using first-principles density functional theory calculations.

Importance of Achievement

Innocuous isoelectronic dopants can act as “vacancy collectors” that attract undesirable vacancies to inactive areas of a 2D chalcogenide device, thanks to their strong coupling with vacancies.

Unique Features of the MIP That Enabled Project

Close collaboration between synthesis, characterization, and theory efforts.


A. Azizi, Y. Wang, G. Stone, A. L. Elias, Z. Lin, M. Terrones, V. H. Crespi, and N. Alem, “Defect Coupling and Sub-Angstrom Structural Distortions in W1–xMoxS2Monolayers”, Nano Lett. 17, 2802 (2017).

Left Image Title: Electron Microscope Image. Left Image Caption: A sulfur vacancy can be seen to pair with a molybdenum dopant in a electron microscope image. Right Image Title: Defect-Pair Structure. Right Image Caption: Defect-pair structure is confirmed by quantum chemical calculations as shown in the right panel.
Azizi, Wang, Stone, Elías, Lin, Terrones, Crespi, Alem, Penn State
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