Epitaxial growth and structural properties of conductive RuO2 thin films

Metal-organic chemical vapor deposition (MOCVD) has been used to deposit co nductive oxide RuO2 thin films at different temperatures on (100) MgO and ( 100) LaAlO3 substrates. The microstructural properties of the RuO2 films ha ve been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). Different growth and microstructural properties were ob served for the films deposited on the two substrates. For example, the film s on MgO are epitaxial at deposition temperatures as low as 350 degrees C, and the films on LaAlO3 are epitaxial only at deposition temperatures of 60 0 degrees C and above. The epitaxial films on MgO consist of two variants w ith an orientation relationship given by (110) RuO2//(100) MgO and [001] Ru O2//[011]MgO. The epitaxial films on LaAlO3, on the other hand, contain fou r variants with an orientation relationship given by (200)RuO2//(100)LaAlO3 and [011] RuO2//[011] LaAlO3. The difference in growth and microstructural properties were explained based on geometrical considerations for the film and substrates. The RuO2/substrate interfaces and the RuO2 domain boundari es were also investigated by TEM and HREM.