Nucleation kinetics of twins in bulk β-Ga2O3 crystal

The twin boundary (TB) is a planar defect that both destroys the integrity of the crystal and significantly deteriorates the performance of semiconductor devices. However, limited research exists on the initial crystal nucleus kinetics of TB, which is a crucial aspect for a comprehensively understanding the twinning mechanism. Here, the nucleation kinetics process of TB has been thoroughly studied regarding crystal morphology, growth interface at the atomic scale, and first-principle calculations in β-Ga2O3. The nucleation kinetics process of TB originates from the smooth interface growth mode of (100)-B, which requires a significant degree of supercooling. During the crystal growth, the large degree of supercooling in front of the (100)-B plane at the three-phase boundary (TPB) leads to nucleation of TB. Twin-B is the recognized twin type of β-Ga2O3 among the two thermodynamically equivalent structures. It is a glide reflection twin whose glide process initiates with a 1/4 length of the [001] vector and then with a 1/2 length of the [010] vector. This study has developed the nucleation kinetics of TB, thus enriching the theory of crystal defects. The revealed relationship between TB and the smooth interface growth mode holds great significance for guiding the suppression of twins.