Effect of lattice constraint on structural stability and miscibility of (Al x Ga1−x )2O3 films: a first-principles study

• Published in: Japanese Journal of Applied Physics Vol. 62; no. SC; p. SC1031
• Main Authors: Fujita, Shuri, Akiyama, Toru, Kawamura, Takahiro, Ito, Tomonori
• Format: Journal Article
• Language: English
• Published: Tokyo IOP Publishing 01.04.2023; Japanese Journal of Applied Physics
• Subjects: Al; Aluminum oxide; Buffer layers; Constraints; Density functional theory; Electronic structure; First principles; Miscibility; stability; Stability analysis; Structural stability; Substrates
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/acae5f

The structural stability and miscibility of (AlxGa1−x)2O3 alloys are theoretically investigated by means of electronic structure calculations within density functional theory. Effects of lattice constraint due to α-Al2O3(0001) substrate and (Al0.4Ga0.6)2O3 buffer layer on the structural stability and miscibility are evaluated from the energy differences and the excess energies among α, β, and κ phases. For the constrained systems by α-Al2O3(0001) substrate, only (AlxGa1−x)2O3 alloys with α phase are found to be stabilized. Furthermore, the lattice constraint drastically improves the miscibility of (AlxGa1−x)2O3 alloys. These results suggest that the lattice constraint is crucial for the stability and miscibility of (AlxGa1−x)2O3 alloys.