β-Ga2O3 on Si (001) grown by plasma-assisted MBE with γ-Al2O3 (111) buffer layer: Structural characterization

• Published in: AIP advances 2021-04, Vol.11 (4), p.045209-045209-10
• Main Authors: Hadamek, Tobias, Posadas, Agham B., Al-Quaiti, Fatima, Smith, David J., McCartney, Martha R., Demkov, Alexander A.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Buffer layers; Electron beams; Electron diffraction; Electrons; Gallium oxides; High energy electrons; Molecular beam epitaxy; Photoelectrons; Structural analysis; Thin films; Transitional aluminas; X ray reflection
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/5.0044923

β-Ga2O3 was deposited in thin film form by plasma-assisted molecular beam epitaxy at 670 °C and 630 °C onto a γ-Al2O3 (111) buffer layer grown at 840 °C by e-beam evaporation on a clean Si (001) surface. The β-Ga2O3 film was 66 nm thick, stoichiometric, and strongly textured, as determined by x-ray reflectivity, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, x-ray diffraction, and transmission electron microscopy, with three basal growth planes (2̄01), (101), and {310}, including one twin variant {31̄0}. The observed basal growth planes correspond to the close-packing planes of the distorted face-centered cubic oxygen sublattice of β-Ga2O3. Local structural ordering can be thought to occur due to a continuation of the oxygen sublattice from the γ-alumina buffer layer into the β-gallia film. Each β-Ga2O3 growth plane further gives rise to 12 symmetry-derived rotational in-plane variants, resulting in a total of 48 domain variants. Atomistic models of possible gallia–alumina interfaces are presented.