posted on 2023-08-22, 20:47authored byReynolds Dziobek-Garrett, Sachi Hilliard, Shreya Sriramineni, Ona Ambrozaite, Yifei Zhu, Bethany M. Hudak, Todd H. Brintlinger, Tomojit Chowdhury, Thomas J. Kempa
Chemical synthesis is a compelling alternative to top-down
fabrication
for controlling the size, shape, and composition of two-dimensional
(2D) crystals. Precision tuning of the 2D crystal structure has broad
implications for the discovery of new phenomena and the reliable implementation
of these materials in optoelectronic, photovoltaic, and quantum devices.
However, precise and predictable manipulation of the edge structure
in 2D crystals through gas-phase synthesis is still a formidable challenge.
Here, we demonstrate a salt-assisted low-pressure chemical vapor deposition
method that enables tuning W metal flux during growth of 2D WSe2 monolayers and, thereby, direct control of their edge structure
and optical properties. The degree of structural disorder in 2D WSe2 is a direct function of the W metal flux, which is controlled
by adjusting the mass ratio of WO3 to NaCl. This edge disorder
then couples to excitonic disorder, which manifests as broadened and
spatially varying emission profiles. Our work links synthetic parameters
with analyses of material morphology and optical properties to provide
a unified understanding of intrinsic limits and opportunities in synthetic
2D materials.