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

In this work, a comprehensive computational fluid dynamics (CFD) investigation to develop an in-depth understanding on the fluid flow to obtain a homogenous deposition of MoS2 thin film is reported. First, the effect of substrate orientations (0, 20, 45, 70, and 90 degrees) was simulated using ANSYS Fluent. The horizontal substrate (0 degrees) showed a non-uniform surface deposition rate (SDR) with relative standard deviation (RSD) of 44.1 %. The non-uniformity gradually reduces with the increase of substrate angles and reaches the lowest for 90 degrees with RSD of 13.1 %. The transient state analysis showed that no growth occurred for the first 8 s, followed by an SDR overshoot and finally reached a steady state >200 s. Next, the effect of horizontal separation distance (d =1 to 6 cm) between MoO3 and the substrate is investigated. It is find that the Mo/S ratio reduces with the increase of separation distance. For d between 5 and 6 cm, the Mo/S drops by >1000 times and causes the growth environment to switch from Mo to S-rich. This work offers a fast and cost-effective approach to understand the fluid flow and to obtain a homogeneous deposition of MoS2 and other 2D TMD thin films.