High-performance BiFe0.95Mn0.05O3 ferroelectric film epitaxially integrated on GaN substrate with LSMO/TiO2 bi-layer buffer

The highly (1 1 1)-oriented BiFe0.95Mn0.05O3 (BFMO) films owning excellent ferroelectric performance have been epitaxially grown on (0 0 0 2) GaN substrates with La0.7Sr0.3MnO3 (LSMO)/TiO2 bi-layer buffer by pulsed laser deposition. By means of the LSMO/TiO2 bi-layer buffer, the lattice mismatch between perovskite (1 1 1) BFMO and wurtzite (0 0 0 2) GaN was miraculously decreased from 12.4% to 1.4%. The remnant ferroelectric polarization and coercive field of the BFMO (1 1 1) film were determined to be 115 μC/cm2 and 450 kV/cm, respectively. Compared with the BFMO film deposited on the bare GaN substrate, the remnant ferroelectric polarization was enhanced by 92%. The piezoresponse force microscopy (PFM) image further confirmed that the BFMO (1 1 1) film owned perfect ferroelectric switching properties.