Epitaxial growth of monoclinic and cubic ZrO₂ on Si(100) without prior removal of the native SiO₂

High-quality epitaxial thin films of pure and yttria-stabilized ZrO₂ (YSZ) were deposited onto Si(100) by electron beam evaporation at substrate temperatures around 880°C. No specific wafer cleaning was employed to remove the native SiO₂. X-ray diffraction revealed a monoclinic structure for the pure ZrO₂, whereas a cubic structure was observed for the YSZ. X-ray pole figure analysis showed that in both cases the in-plane axes of the films were essentially parallel to the Si[010] and [001] directions. Rutherford backscattering and channelling analysis resulted in minimum yield values of 7% and 6% for the pure ZrO₂ and the YSZ films respectively, thus indicating a high degree of crystalline perfection. A 20 Å thick amorphous SiO₂ layer was observed at the interface using high resolution transmission electron microscopy. It was probably regrown during film deposition, after the original surface oxide of the wafer had been removed in situ.