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Catalyzed Kinetic Growth in Two-Dimensional MoS2
journal contribution
posted on 2020-07-13, 20:31 authored by Lingli Huang, Quoc Huy Thi, Fangyuan Zheng, Xin Chen, Yee Wa Chu, Chun-Sing Lee, Jiong Zhao, Thuc Hue LyIt
remains difficult to control the morphology of two-dimensional
(2D) materials via direct chemical vapor deposition (CVD) growth.
In particular, off-equilibrium (kinetic) growth may produce flakes
with non-Wulff shapes (e.g., high-index edges, symmetrical shapes,
etc.), which are potentially useful; however, a general controllable
approach for the kinetic growth of 2D materials is currently lacking.
In this work, we pushed the CVD growth of 2D MoS2 into
deep kinetic regime, by using potassium chloride (KCl) as catalyst
and plasma pretreatment on growth substrates. The unprecedented nonequilibrium
high-index faceting and unusual high-symmetry shapes in 2D materials
have been realized. The growth mechanism of high-index facets is rationalized
based on the theory of kinetic instability on crystal surfaces. This
new vapor–liquid–adatom–solid (VLAS) growth mechanismsynergistic
capture of multiple vapor phase molecules by the catalyst particles
on corners and the oversaturated adatom diffusion along adjacent edges
can offer great opportunities for shape engineering on 2D materials.
The high-quality, rapid, and controllable synthesis of high-index
facets (edges) and other non-Wulff shapes of 2D transition metal dichalcogenides
will benefit the developments in 2D materials.