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

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Metalorganic Chemical Vapour Deposition (MOCVD) is an attractive method for depositing thin films of cadmium telluride (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 scale-up of II-VI MOCVD reactors. This paper presents the results of CFD modelling 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 total flow rate, reactor pressure and substrate temperature on the deposition behaviour has been assessed. In the present study, dimethylcadmium (DMCd) and diisopropyltelluride (DiPTe) have been used as precursors while H2 is acting as the carrier gas and N2 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.