Fabrication of single ferroelectric films on silicon substrates by interface control

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B_4Ti_3O_12(BIT) thin films were epitaxially grown on epitaxial Pt and Ir films by reactive sputtering with Ar and 0_2 mixed gas, where the epitaxial Pt and Ir films were deposited on epitaxial (100)YSZ/(100) Si substrate structures by sputtering with Ar gas. The X-ray diffraction patterns showed that the epitaxial BIT films were grown on the (100) Ir and Pt films with in-plane rotation of 45° from cube on cube crystallographic relationship, However, Rutherford backscattering spectroscopy showed that many voids exist in the BIT films and interdiffusion of components among Ir, BIT and YSZ films occurs, This is because the Ir film was oxidized due to diffused O through the Ir film during the BIT film deposition, which induced other reaction among other components, On the other hand, it was found that the BIT film on the Pt film had normal density and no void and that it hardly reacted with other films. We can observe the hysteresis with a small loop from the BIT film on the Pt film, but hardly observe one from the Ir film. Therefore, we can speculate that the inter-reaction or interdiffusion among the films is one possible factor to prevent generation of the ferroelectric property of the BIT film on the Ir film. Also, on the (111) Pt film, it was found that BIT film was not perovslaite phase with ferroelectric property, but is pyrochlore phase. This result suggests us that it is necessary to grow the (100) Pt film on the YSZ film in order to obtain a BIT film with the (001) orientation.