Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111) substrates by intermittent microwave assisted hydrothermal method

We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111) substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO3)4− or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111) and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111) substrates. Bi(NO3)3 and Fe(NO3)3 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100) substrates was verified by piezoresponse force microscopy.