Orientation-dependent atomic-scale mechanism and defect evolution in β-Ga2O3 thin film epitaxial growth.

β-Ga₂O₃ has been subjected to intense research interest as an ultrawide bandgap semiconductor. The epitaxial growth technique of β-Ga₂O₃ thin films plays a fundamental and vital role in Ga₂O₃-based device fabrication. In this work, the epitaxial growth mechanisms of β-Ga₂O₃ on four low-Miller-index facets, (100), (010), (001), and ( 2 ¯ 01), are systematically explored using large-scale machine-learning molecular dynamics simulations at the atomic scale. The simulations reveal that the migration of the face-centered cubic stacking O sublattice plays a dominant role in the different growth mechanisms between the (100)/(010)/(001) and ( 2 ¯ 01) orientations. The resultant complex combinations of the stacking faults and twin boundaries are carefully identified and show good agreement with experimental observations and ab initio calculations. Our results provide useful insights into the gas-phase epitaxial growth of β-Ga₂O₃ thin films and suggest possible ways to tailor its properties for specific applications. [ABSTRACT FROM AUTHOR]