Abstract: A mathematical model of metal-organic chemical vapor deposition (MOCVD) process is developed to understand the growth mechanism of GaAs films within a horizontal reactor. Two-dimensional numerical simulation on the reactive gas flow is performed based on the semi-implicit method for pressure-linked equations (SIMPLE). Moreover, the theories of boundary layer on momentum, heat and mass transfer are used to analyze transport of chemical components and heat transfer between the reactor and gas during film preparation. The calculated GaAs growth rate is in agreement with the experimental results, indicating the impacts of intake air flow rate, operating pressure and temperature on the GaAs growth rate. It is revealed that, within the scope of the paper, the film growth rate increases with the rise of inlet gas velocity, while the film gradually exhibits inhomogeneity. Consequently, a flow rate of 0.104 m/s is chosen. By increasing the operating pressure, the film growth rate is increased, evidenced by the GaAs growth rate of 223% at 6 kPa, higher than that for the case of 2 kPa. In other words, it has a higher growth rate and better uniformity. Furthermore, the substrate temperature is a significant effect on the film growth rate as well. The condition of 1 050 K has a high growth rate and good uniformity, with GaAs growth rate being 123% higher than that of 950 K. The present study provides a theoretical understanding for optimizing the reaction conditions and the structure of MOCVD.

Key words: diffusion boundary layer, film growth rate, GaAs, metal-organic chemical vapor deposition (MOCVD), numerical simulation