Determining Equilibrium Shapes of MoS₂: Modified Algorithm, Edge Reconstructions with S and O, and Temperature Effects
2021
Sin, Chuen-Keung | Zhu, Junyi
Equilibrium shape is the prerequisite to fully understanding the growth dynamics of quasi-2D structures, like transition metal dichalcogenides. However, the intrinsic complexity of the quasi-2D nature and the complex growth environment for the edge reconstruction make it challenging to formulate a successful algorithm along with proper thermodynamic analysis. As a result, theoretical investigations on the growth thermodynamics and kinetics of MoS₂ failed to explain all the relevant equilibrium shapes in the contemporary chemical vapor deposition synthesis, changing from triangle to hexagon then back to triangle when the condition is changed from the Mo-rich to S-rich limit. This reveals that there should be a missing piece of jigsaw puzzle in the understanding of edge thermodynamics. To answer this question, we proposed a modified calculation scheme under the assumption of the octet rule surrounding anion atoms with charge transfers allowed by pseudo-H passivation, considering edge reconstructions with S and O, and taking temperature effects into account so as to unveil the mystery of morphological changes of MoS₂ under different experimental conditions.
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