Piezoelectric Ba and Ti co-doped BiFeO3 textured films: selective growth of solid solutions or nanocomposites

Abstract

Metal organic chemical vapor deposition (MOCVD) is exploited as a synthetic route to produce Ba and Ti co-doped BiFeO₃ thin films. A facile approach based on a molten multi-component source, consisting of a Bi(phenyl)₃, Fe(tmhd)₃, Ba(hfa)₂·tetraglyme and Ti(tmhd)₂(O-iPr)₂ (phenyl = –C₆H₅, H-tmhd = 2,2,6,6-tetramethyl-3,5-heptandione; O-iPr = iso-propoxide; H-hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; tetraglyme = CH₃O(CH₂CH₂O)₄CH₃) mixture, is applied for the MOCVD based fabrication of doped BiFeO₃ films on SrTiO₃:Nb(100) substrates. The applied characterization techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM), provide a suitable correlation between processing parameters/precursor mixtures and the nature of the deposited films, in terms of the formation of solid solutions of the type Bi_(1−x)Ba_xFe_(1−y)Ti_yO₃vs. the formation of Bi_(1−x)Ba_xFeO₃/Bi_(1−x)Ba_xFe_(1−y)Ti_yO₃ nanocomposite films. Piezoresponse force microscopy (PFM) is applied to correlate the nanostructure/composition and piezoelectric/ferroelectric properties.