Numerical modelling of Cz- β-Ga2O3 crystal growth in reactive atmosphere

The present study focuses on computer modeling of Cz- β-Ga2O3 crystal growth while also addressing the issue of minimizing Ir crucible oxidation. To accomplish this objective, a comprehensive framework was developed that combines thermodynamic equilibrium calculations with a CFD numerical model. This integrated approach is designed to simulate the impact of SO2 gas concentration in the chamber atmosphere. The primary goal of this numerical model is to assess deviations from the stoichiometric ratio in the Ga2O3 melt by examining the processes taking place at the free surface of the melt and their effects on its stoichiometry. These processes include the dissociation of the Ga2O3 melt into Ga and O ions, as well as the evaporation of volatile species from the melt surface. Simulations were conducted for both 2-inch and 4-inch crystals, with varying concentrations of SO2 and CO2 in an Ar atmosphere, facilitating a direct comparison between the two gases. The study's findings indicate that the optimal concentration of SO2 in the atmosphere should be approximately 40%, whereas for CO2, the optimal concentration is around 9%. Significantly reduced concentrations of both SO2 and CO2 were achieved by increasing the free melt surface area. Notably, the atmosphere with a SO2 concentration exhibited a substantial 30% reduction in the O concentration surrounding the crucible, underlining the advantages of using SO2 as a viable alternative to CO2.