Epitaxial growth of SrRuO₃ thin film electrode on Si by pulsed laser deposition

Pseudocubic SrRuO₃ (100) epitaxial thin films were fabricated on Si (100) with a SrO buffer layer by pulsed laser deposition (PLD). Reflection high-energy electron diffraction (RHEED) revealed that the SrO layer is epitaxially grown on naturally oxidized Si substrates with an orientation relationship of SrO (110)/Si (100) and SrO 〈001〉//Si (011). Subsequent SrRuO₃ deposition resulted in a (100) epitaxial thin film possessing good crystallinity with a full-width at half maximum (FWHM) of 1.9° in the SrRuO₃ (200) rocking curve by X-ray diffraction (XRD). Based on the Gibbs free energy change in the reaction of silicon with alkaline earth metal oxides, deoxidization of SiO₂ on Si by Sr is thought to play an important role in the epitaxial growth of SrO. Cross-sectional observation for the optimized SrRuO₃/SrO/Si sample using transmission electron microscopy (TEM) revealed that the thickness of the SrO layer is less than 2nm and that the SrRuO₃ electrode forms an epitaxial thin film almost directly on Si.