Abstract
High-quality Gd <sub>2</sub> O <sub>3</sub> epi-films 5-20 nm thick have been grown on GaN (0001) using molecular beam epitaxy. A detailed structural investigation was carried out by in situ reflection high energy electron diffraction, cross sectional transmission electron microscopy, and X-ray scattering using a synchrotron radiation source. The films consist of the high-temperature monoclinic (m) phase with six rotational domains, which can be easily mistaken for being the hexagonal phase. All the domains follow the m-Gd <sub>2</sub> O <sub>3</sub> (2̄01)<020> ∥ GaN (0001)<112̄0> orientational relationship. © 2010 American Chemical Society.