Promoting Crystal Distribution Uniformity Based on the CVD Method with the Aid of Finite Element Methods

Abstract

Two-dimensional materials, including transition-metal dichalcogenides (TMDs), have aroused wide interest due to their various applications in gas sensors and photoelectric devices. However, achieving a uniform distribution of materials on the substrate is still a challenging and urgent problem. In this article, the factors influencing the material distribution during the chemical vapor deposition process are investigated by a simulation method, and the results show that the unequal velocity distributions caused by the carrier gas flow on the growing surface play an important role in influencing the crystal distribution. Boundary layer theory is used to explain the mechanism of the effect of the carrier gas flow on the growth uniformity. An improved method is proposed to improve the material uniformity by changing the placement of the Si/SiO2 substrate from face down to face up. The simulation and experimental results show that uniformly distributed MoS2 with a large size and good quality can be obtained with the improved method. This work provides a method for preparing uniformly distributed TMDs on a substrate, which should facilitate subsequent research of two-dimensional materials and promote the application of two-dimensional materials.

Combined Experimental and Computational Insight into the Role of Substrate in the Synthesis of Two-Dimensional WSe2

“…The final structure’s layer count, size, and orientation can be precisely tuned by manipulating various process parameters, including substrate type and orientation. A wide array of computational approaches, including finite element analysis, − atomistic simulation, , and first-principles method, has been harnessed to provide insights into the synthesis of 2D material. − While the majority of these investigations primarily center around first-principles/density functional theory (DFT) calculations, their scope remains limited in analyzing larger atomic systems found in TMDs exhibiting specific rotation angles. Consequently, it becomes imperative to employ alternative simulation techniques such as molecular dynamics (MD), , phase-field, , or multiscale models − to gain a comprehensive understanding of the underlying mechanisms governing their growth.…”

Computational Fluid Dynamics Insights into Chemical Vapor Deposition of Homogeneous MoS2 Film with Solid Precursors

“…[23] For 2D TMDs, Zhou et al investigated the optimum boat geometry to grow a uniform MoSe 2 while Zhang et al reported velocity distribution of face-up or face-down substrate orientations. [24,25] However, analyses on surface deposition rate and precursors molar concentration were not discussed. Despite the potential of CFD in assisting the experiments, the simulation must be carried out with great care to ensure the accuracy of the predicted results.…”

Effect of the Substrate on MoS2 Monolayer Morphology: An Integrated Computational and Experimental Study

“…Then the product of gaseous reactions deposits on the substrate, forming the 2D monolayer material. Various computational methods such as finite element analysis, − atomistic simulation, , and the first-principle method have been employed to guide the synthesis of 2D materials. ,− Although most of these studies focus on first principal/DFT calculations, these simulations cannot analyze larger atomic systems involved in TMDs with certain rotation angles. Thus, in order to understand the mechanisms underlying their growth, other simulation techniques such as molecular dynamics (MD), phase-field, , or multiscale models − need to be used.…”