Nanoscale ferroelectric tunnel junctions based on ultrathin BaTiO₃film and Ag nanoelectrodes

Abstract

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 (∼3 nm thick) exhibit both apparent ferroelectric polarization reversal and ferroelectric tunneling related resistive switching behaviors. The introducing of Ag nanoislands (∼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.