Orientation-Dependent Domain Structure and Buffer Layer Functionality of Epitaxial Bixbyite Sc2O3 Thin Films

Abstract

We report the epitaxial growth of high-quality bixbyite-structured Sc2O3 thin films on differently oriented Yttria-stabilized Zirconia (YSZ) substrates by radio-frequency magnetron sputtering. Films grown along the ⟨111⟩ orientation exhibit atomically flat surfaces, full structural relaxation, and a single rotational variant, as confirmed by X-ray diffraction and scanning transmission electron microscopy. In contrast, ⟨001⟩-oriented films display rotational domains and residual tensile strain, while ⟨110⟩-oriented films exhibit a columnar morphology with significantly higher surface roughness. When we use ⟨111⟩-oriented Scandia-buffered YSZ substrates to grow hexagonal YMnO3 thin films, we stabilize them in a compressive strain state. These results establish Sc2O3 epitaxial films as promising virtual buffer layers for the growth of functional oxides.