Improving Epitaxial Growth of γ‐Al₂O₃ Films via Sc₂O₃/Y₂O₃ Oxide Buffers

Heteroepitaxial growth of γ‐Al 2 O 3 on Sc 2 O 3 /Y 2 O 3 /Si (111) is achieved with oxygen plasma‐assisted molecular beam epitaxy in order to prevent polycrystalline grain boundary formation caused by lattice mismatch. Substrate temperature as well as oxygen flow are adjusted to optimize epitaxial growth conditions around 715–760 °C and 1.9 sccm, respectively. Epitaxial growth is monitored in situ by reflection high‐energy diffraction, while surface morphology is studied by scanning electron microscopy ex‐situ. X‐ray diffraction indicates epitaxial out‐of‐plane 111 orientation with oxygen flow above 0.6 sccm. However, transmission electron microscopy shows stacking fault formation for high oxygen flows. Finally, nanobeam electron diffraction confirms Smrčok model of a spinel‐like γ‐Al 2 O 3 crystal structure.