Abstract
Ferroelectric SrBi2Ta2O9 (SBT) thin films have been formed on silicon substrates at a crystallization temperature as low as 750 oC. The crystallization atmosphere (O2, N2, H2O-vapor/N2) influenced the electrical characteristics of the Au/SBT/p-Si structures. The capacitance-voltage characteristics of the devices suggested that the defects in the interface region were smallest as the SBT film was crystallized in the H2O-vapor/N2 atmosphere. The effect of the crystallization atmosphere on the SBT film and interface structures were quantitatively investigated by using X-ray reflectivity (XRR) method. It was confirmed that an interfacial layer was formed between the SBT film and the silicon substrate in any case. The interfacial layer was thickest in the case of H2O-vapor/N2 atmosphere. However, the density of the interfacial layer was independent of the crystallization atmosphere. Furthermore, the crystallization duration dependence showed that the thickness of the interfacial layer increased with crystallization duration but the density remained a value ~2.5 g/cm3. The interfacial layer formation was mainly caused by oxidation of silicon.
