Heteroepitaxial growth of RuO₂ thin films on α-Al₂O₃ substrates with CeO₂ buffer layers by pulsed laser deposition

Metallic conductive ruthenium oxide thin films have been grown epitaxially on sapphire (01 1 2) with a cerium oxide buffer layer by pulsed laser deposition. We used transmission electron microscopy, high-resolution electron microscopy, and x-ray diffraction to characterize the growth behavior of the films and the orientation relationship between the films and the substrate. Our electron diffraction and x-ray diffraction studies indicate that the orientation relationships are (200)_RuO2//(200)_CeO2//(0112)_Al2O3 and 〈011〉_RuO2//〈001〉 _CeO2//〈2201〉_Al2O3. All of the interfaces were seen to be atomically sharp by cross-sectional, high-resolution transmission electron microscopy in the as-grown samples. No precipitates or additional phases were found in the films or at their interfaces.