Epitaxial stabilization of pseudomorphic α-Ga2O3 on sapphire (0001).

Heteroepitaxial Ga₂O₃ was grown on c-plane sapphire by molecular beam epitaxy, pulsed-laser deposition, and metalorganic chemical vapor deposition. Investigation by scanning transmission electron microscopy (STEM) revealed the presence of a three-monolayer-thick pseudomorphically grown layer of trigonal α-Ga₂O₃ at the interface between the c-plane sapphire substrate and the β-Ga₂O₃ independent of the growth method. On top of this pseudomorphically grown layer, plastically relaxed monoclinic β-Ga₂O₃ grew in the form of rotational domains. We rationalize the stable growth of the high-pressure trigonal α-phase of Ga₂O₃ in terms of the stabilization of the α-Ga₂O₃ phase by the lattice-mismatch-induced strain. [ABSTRACT FROM AUTHOR]