Nanoscale ferroelectric tunnel junctions based on ultrathin BaTiO3 film and Ag nanoelectrodes

In this work, Ag nanoisland electrodes (nanoelectrodes) have been deposited on top of ultrathin ferroelectric BaTiO3 (BTO) films to form a nanoscale metal-ferroelectric-metal tunnel junction by integrating growth techniques of nanocluster beam source and laser-molecular beam epitaxy. The ultrathin BTO films (similar to 3 nm thick) exhibit both apparent ferroelectric polarization reversal and ferroelectric tunneling related resistive switching behaviors. The introducing of Ag nanoislands (similar to 20 nm in diameter) as top electrode substantially enhances the tunneling current and alters the symmetry of I-V hysteresis curves. The enhanced tunneling current is likely due to the reduction in tunneling barrier height and an increase in effective tunneling area by Ag nano-electrodes, while the improved symmetric in I-V curve may be attributed to the variation of electrode-oxide contact geometry. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4756918]