Thermodynamic analysis of β-Ga2O3 growth by molecular beam epitaxy

Thermodynamic analyses of beta-Ga2O3 growth by both ozone and plasma-assisted molecular beam epitaxy (MBE) were performed. In either case, the growth mechanism was found to differ depending on whether the input VI/III ratio was above or below 1.5. Under O-rich conditions (VI/III > 1.5), the driving force for beta-Ga2O3 growth (Delta P-Ga2O3) was determined to increase linearly with increasing Ga input partial pressure (P-Ga degrees) because almost all the supplied Ga was used for the growth of the beta-Ga2O3. In contrast, Ga-rich conditions (VI/III < 1.5) caused Delta P-Ga2O3 to decrease. Etching of the beta-Ga2O3 occurred with increasing P& due to the formation of volatile Ga2O. This work also demonstrated that the use of ozone allowed growth at higher temperatures than the use of O radicals. The calculated results were in good agreement with experimental values, indicating that beta-Ga2O3 growth by MBE can be explained by thermodynamics. (C) 2022 The Japan Society of Applied Physics