Fabrication of homogeneous nanoparticle/nanoneedle BaTiO₃ and Ba_0.8Sr_0.2TiO

Abstract

Ferroelectric BaTiO₃ (BTO) and Ba_0.8Sr_0.2TiO₃ (BSTO) thin film materials have been successfully prepared by sol-gel processing and simple dip coating on glass and silicon supports. Above thin films were characterised by X-ray diffraction (XRD), Raman spectroscopy, photoelectron spectroscopy, thermal analysis, atomic force microscopy (AFM) and spectroscopic ellipsometry. Phase identification of BaTiO₃ and Ba_0.8Sr_0.2TiO₃ was performed by XRD. XRD and Raman spectroscopy investigations demonstrate that the Ba_0.8Sr_0.2TiO₃ film exhibits tetragonal structure. AFM analysis demonstrates the elongated nanospherical particles on glass substrate and nanowires on silicon substrate, which represent a strong influence of the crystallinity of underlying substrate on the grain morphology in this technique. The thin films on both the substrates are uniformly coated without any pinhole to a significant area (~2.5 cm²), and this method might be extended to large area uniform coating. Spectroscopic ellipsometric measurements reveal the exact thickness, refractive index and extinction coefficient of the thin films.