Adv Mater. 2021 Nov 5:e2106674. doi: 10.1002/adma.202106674. Online ahead of print.
ABSTRACT
Defects are ubiquitous in 2D materials and can not only affect the structure and properties of the materials but can also introduce new functionalities. Methods to adjust the structure and density of defects during bottom-up synthesis are required to control the growth of 2D materials with tailored optical and electronic properties. In this paper, w e present a Au-assisted chemical vapor deposition approach to selectively form SW and S2W antisite defects, whereby one or two sulfur atoms substitute for a tungsten atom in WS2 monolayers. Guided by first-principles calculations, w e describe a new method that can maintain tungsten-poor growth conditions relative to sulfur via the low solubility of W atoms in a gold/W alloy, thereby significantly reducing the formation energy of the antisite defects during the growth of monolayer WS2 . The atomic structure and composition of the antisite defects are unambiguously identified as SW and S2W by Z-contrast scanning transmission electron microscopy and electron energy-loss spectroscopy, and their total concentration is statistically determined, with levels observed up to ∼5.0%. Scanning tunneling microscopy/spectroscopy measurements and first-principles calculations further verified these antisite defects and revealed the localized defect states in the bandgap of WS2 monolayers that are candidates for single photon emitters. This bottom-up synthesis method to form antisite defects should apply in the synthesis of other 2D transition metal dichalcogenides. This article is protected by copyright. All rights reserved.
PMID:34738669 | DOI:10.1002/adma.202106674
