Numerical model of species transport and melt stoichiometry in β-Ga2O3 crystal growth

Abstract

In current work, we present a computer model, which describes the processes responsible for the loss of melt stoichiometry: dissociation of gallium oxide melt into gallium and oxygen ions, independent evaporation of the melt components from the free surface into the gas atmosphere, and loss of the melt stoichiometry. The mass transport model is coupled with heat transfer and calculation of the melt and gas flows. It also incorporates the effect of CO2 added to the growth atmosphere.Model operation was demonstrated for 2-inch β-Ga2O3 crystal growth process by Czochralski method with various amounts of added CO2 and predicted reduction of melt non-stoichiometry with addition of carbon dioxide to the gas mixture. Several modifications of the hot zone design have been considered in terms of their effect on the melt stoichiometry. Area of the melt free surface was found to have the most pronounced and non-linear effect on the amount of CO2 required to compensate the loss of oxygen.