Numerical simulation of the deposition process and the epitaxial growth of cadmium telluride thin film in a MOCVD reactor

摘要

Metalorganic chemical vapor deposition (MOCVD) is an attractive method for depositing thin films of cadmium tel-luride (CdTe) and other group II-VI compound materials. It has been known that the growth rate of CdTe thin film is sensitive to the substrate temperature and the reactant partial pressures, indicating that the deposition process is kinetically controlled and affected by many conditions. In the deposition process, heterogeneous reactions play an important role in film formation, and the process is further complicated by the coupling of gas and surface reactions via desorption of the reactive intermediates. A detailed understanding of the deposition mechanism and kinetics will be crucial for the design, optimization, and scaling up of II-VI MOCVD reactors. This paper presents the results of computational fluid dynamics (CFD) modeling of the deposition process in an inline MOCVD reactor, taking into account the heat transfer and mass transport of the chemical species. The numerical simulations have been conducted using the CFD code, ANSYS FLUENT. The influence of the process controlling parameters such as the total flow rate, reactor pressure, and substrate temperature on the deposition behavior has been assessed. In the present study, dimethylcadmium and diiso-propyltelluride have been used as precursors while H_2 acts as the carrier gas and N_2 as the flushing gas. The capabilities of using the developed CFD models for revealing the deposition mechanisms in MOCVD have been demonstrated. The simulations have been conducted in both mass transport and kinetics regimes at the temperature range of 355-455° to match the experimental conditions.