Formation energy crossings in Ga2O3-Al2O3 quasibinary system: ordered structures and phase transitions in (Al x Ga1-x )2O3

A quasibinary system of Ga2O3-Al2O3 offers a range of applications in wide bandgap semiconductor engineering. Different polymorphs and concentrations of (Al (x) Ga1-x )(2)O-3 manifest a variety of structural and electronic properties, paving the way for tunability of (Al (x) Ga1-x )(2)O-3 for specific functions. In this work, we investigate the energetics of alpha (alpha) and beta (beta) polymorphs of Ga2O3 and Al2O3 by considering all possible configurations in a conventional unit cell. Using density functional theory, we show that the formation energies of (Al (x) Ga1-x )(2)O-3 in alpha and beta configurations start to coincide at 50% concentration (Al0.5Ga0.5)(2)O-3. The corundum configuration then becomes more dominant (lower in energy) than its monoclinic counterpart at around 80% Al concentration. The lowest formation energy configurations for 50% concentration in both alpha and beta polymorphs also manifest a preference towards an ordered phase. These show that the stability of Ga2O3-Al2O3 and its phase transitions are significantly influenced by the relative arrangements of Ga and Al within the quasibinary semiconducting crystal.

Automated summary

A quasibinary system of Ga2O3-Al2O3 is studied in this work, exploring the energetics of different polymorphs and concentrations using density functional theory. It is found that the formation energies of (Al (x) Ga1-x )(2)O-3 in alpha and beta configurations start to coincide at 50% concentration, and the corundum phase becomes more dominant at around 80% Al concentration. The lowest formation energy configurations for 50% concentration show a preference towards an ordered phase, indicating the significant influence of Ga and Al arrangements on the stability and phase transitions of Ga2O3-Al2O3.