Surface Structure and Morphology of SrBi2Ta2O9 (SBT) Thin Films

Abstract

AbstractSrBi2Ta2O9 (SBT) films have been prepared by MOCVD processes. The phase formation, surface structure, morphology and surface roughness of SBT films on Pt/Ti/SiO2/Si wafers were measured by XRD, SEM, AFM and ellipsometry. It was found that amorphous SBT formed below 500°C, amorphous and polycrystalline growth occurred successively between 500°C and 650°C. The surface roughness of the SBT thin films also increased with increasing deposition temperature. The AFM results showed the nucleation of SBT started by island formation, then continued across the surface of substrates at lower deposition temperatures. When the SBT film was deposited at higher temperatures, the nucleation and grain growth occurred at the same time, resulting in an inhomogencous structure and much higher surface roughness. Therefore, a two step process is used to improve surface roughness and interface mismatch between film and substrate. In addition, the relationships between surface structure, morphology and the electric properties of SBT thin films were also investigated.