Fabrication of single ferroelectric films on silicon substrates by interface control

用Ar和O2混合气体反应溅射在外延的铂和Ir薄膜上外延生长了B4Ti3O12(BIT)薄膜，用Ar气体溅射在(100)YSZ/(100)Si衬底结构上制备了外延的铂和Ir薄膜。X射线衍射图表明，在(100)Ir和Pt膜上生长的外延BIT膜与立方晶体关系上的面内旋转为45°，而Rutherford背散射光谱表明BIT膜中存在大量空洞，Ir、BIT和YSZ膜之间发生了组元的互扩散，这是因为在BIT膜沉积过程中，由于Ir膜中的O通过Ir膜扩散而被氧化，从而引发了其他组分之间的其他反应。另一方面，发现铂膜上的BIT膜具有正常的密度，没有空洞，几乎不与其他薄膜反应。我们可以从铂薄膜上的BIT膜上观察到一个小回线，而从Ir膜上几乎观察到一个回线。因此，我们可以推测，薄膜之间的相互反应或相互扩散可能是阻止Ir薄膜上BIT薄膜铁电性质产生的一个可能因素。在(111)Pt膜上，发现BIT膜不是具有铁电性质的钙钛矿相，而是焦绿石相。这一结果表明，为了获得具有(001)取向的BIT膜，必须在YSZ膜上生长(100)Pt膜。

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.