MULT-SCALE MODELLING AND COMPUTATIONAL FLUID DYNAMICS ANALSYIS OF TRANSITION METAL DICHALCOGENIDE (TMD) GROWTH IN AN MOCVD CHAMBER
Open Access
- Author:
- Zafar, Suhaib
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- October 16, 2020
- Committee Members:
- Yuan Xuan, Thesis Advisor/Co-Advisor
Robert Francis Kunz, Committee Member
Karen Ann Thole, Program Head/Chair - Keywords:
- CFD
2D materials
TMDs
MOCVD
Growth Kinetics - Abstract:
- Among semiconductors, Transition Metal Dichalcogenides (TMDs) are a promising new type, offering exciting new possibilities in applications such as light-emitting diodes. A variety of synthesis technologies for TMDs have been reported, foremost of which is the Metal Organic Chemical Vapor Deposition (MOCVD) method. Recently, researchers have applied MOCVD to synthesis of tungsten diselenide (WSe2), which falls under the class of TMDs. To gain a better understanding of WSe2 growth kinetics, researchers have experimented with different substrates, precursors, and various ranges of growth parameters such as temperature and pressure. It is crucial to gain this insight to benefit from its useful properties. Computational Fluid Dynamics (CFD) is a useful complement to experimentation in this regard, and in general is cheaper and faster. However, CFD simulations require a chemical kinetics model to be incorporated with heat transfer and fluid mechanics for it to be a useful analysis and prediction tool. Such models have been developed for other materials such as GaN and have proved useful in analyzing and optimizing growth of semiconductors. In a similar fashion, this thesis presents the use of CFD to analyze the impact of varying process parameters on WSe2 growth in an MOCVD reactor used by researchers at the Penn State 2DCC facility. We utilized a gas-phase chemical kinetics model developed using a multi-scale modeling framework incorporating Density Functional Theory (DFT) and reactive molecular dynamics, presented in a previous study. A comparison of WSe2 and MoSe2 growth kinetics is also done in this context, highlighting key similarities as well as differences. Finally, based on the analysis of results obtained from varying process parameters, the effect of chamber geometry on WSe2 growth was also analyzed using numerical experiments.