Epitaxial Growth of Perovskite (Ba, Sr)TiO₃ Thin Films on Silicon

Epitaxial (Ba_0.5, Sr_0.5)TiO₃ (BST) and yttria stabilized zirconia (YSZ) thin films have been grown by pulsed-laser deposition (PLD) on silicon substrate. It is found that very thin YSZ buffer layer yields the epitaxial growth of BST thin films on Si. Low ambient oxygen pressures are required for growing the YSZ buffer layer whereas the ambient oxygen pressure does not influence the epitaxial growth of BST films. In these double heteroepitaxial structures, the axial relationship is BST[200]/YSZ[200]/Si[100]. As the YSZ buffer layer becomes thicker than 10 nm, the BST films exhibits a polycrystalline nature. Moreover, BST films experienced lattice distortion along the in-plane and surface normal directions due to the stress induced primarily by thermal stress during deposition.