To reduce the Reset current, the HfO-based RRAM device with Ni top electrode (TE) and TiN bottom electrode (BE) is fabricated. Compared to the devices with Al and Ti top electrodes, the Ni/HfO/TiN device cell with the high-work-function Ni TE exhibits the ultra-low Reset current (sub-100nA), bipolar resistive switching, consistent switching with a large window and good data retention. In addition, multilevel storage characteristics are demonstrated by setting different compliance currents during set processes. The ultra-low power characteristic is related to the Schottky barrier at the interface of high-work-function Ni TE and n-type HfO. The mechanisms of resistive switching and current conduction are also analyzed based on the Schottky-barrier modulation.
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