Effect of SrTiO3 buffer layer on the phase formation and properties of direct-patternable BiFeO3 thin films fabricated using photochemical metal-organic deposition

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The formation of BiFeO3 without impurity phases, such as excess bismuth and iron, has been possible in only a narrow pressure-temperature-stoichiometric window. A direct-patterned BiFeO3 film using photochemical metal-organic deposition (PMOD) was fabricated without a conventional etching. BiFeO3 film was formed on a SrTiO3 buffer layer with a perovskite structure and a lattice constant of 3.905 Å in order to study the substrate effect during phase formation. This study showed the phase formation and electrical properties of the direct-patternable PMOD BiFeO3 thin films. The SrTiO3 buffer layer was found to somewhat prevent the formation of a Fe excess phase in BiFeO3 after anneal at 550°C for 20 min under O2 and N2 atmospheres. The measured remnant polarization (Pr) and coercive field (Ec) values of the Pt/BiFeO3(200 nm)/SrTiO3(40 nm)/Pt/Si structure were 10 µC/cm2 and 300 kV/cm, respectively. Leakage current of perovskite BiFeO3 film was found to be dominated by Poole–Frenkel emission as other perovskite ferroelectrics. To obtain an image, a spin-coated BiFeO3 film was exposed to UV for 15 min and then rinsed in hexane. From this work, it was revealed that the direct-patterning of BiFeO3 films could be applicable for the fabrication of micro-patterned systems using a SrTiO3 buffer layer with controlled reactant stoichiometry.