Epitaxial Growth of La-doped BiFeO₃ by Digital RF Sputtering

BiFeO₃ (BFO) has been investigated extensively due to its attractive ferroelectric properties and ability to incorporate in various heterostructures. However, BFO films suffer from high leakage currents, hindering its applicability and performance in devices. One solution to this drawback is the substitution of La at the A-site of BFO, which has been shown to reduce the leakage current densities while preserving its ferroelectric properties. In this work, we present the growth of epitaxial La-doped BFO by digital sputtering. This method allows control of the dopant by altercation of the sputtering cycle, in which the doping concentration is set by the sputtering cycle time of the LaFeO₃ target. High quality epitaxial films were grown by off-axis co-sputtering of the BFO and LaFeO₃ targets. Film quality was characterized by XRD, AFM, and TEM showing epitaxial growth on SrTiO₃(001) and DyScO₃(110), where a SrRuO₃ buffer layer was used as a bottom electrode for ferroelectric characterization. Piezoresponse Force Microscopy was used to image the ferroelectric domains and capacitance hysteresis measurements show the leakage currents for the La-doped BFO films.