Size dependent bipolar resistance switching of NiO nanodots for low-power and multi-state operation.

NiO nanodots of various sizes were fabricated via anodic oxidation induced through atomic force microscopy (AFM) nanolithography on an 18 nm thick Ni thin film, and their resistance switching properties were investigated using conductive AFM. We found that NiO nanodots with a medium size of around 15 nm height showed clear bipolar resistance switching. A threshold switching was observed in the NiO nanodots with a larger size due to having a much thinner bottom Ni layer left after oxidation. By adjusting the range of the sweeping voltage, the high resistance state can be controlled to realize multi-state switching. The power consumption during the switching process induced by the AFM tip was found to be lower than the reported power values of the NiO thin film-or NiO nanowires-based resistance switching devices.