Reset First Resistive Switching in NiO Thin Films as Charge Transfer Insulator Deposited by Reactive RF Magnetron Sputtering.

Reset-first resistive random access memory (RRAM) devices were demonstrated for off-stoichiometric NiO thin films deposited using reactive sputtering with a high oxygen partial pressure. The NiO based RRAM devices exhibited both unipolar and bipolar resistive switching characteristics without an electroforming step. Auger electron spectroscopy showed nickel deficiency in the NiO films, and X-ray photoemission spectroscopy showed that the Ni valence state in the NiO films increased with increasing oxygen partial pressure. Conductive atomic force microscopy showed that the conductivity of the NiO films increased with increasing oxygen partial pressure during deposition, possibly contributing to the reset-first switching of the NiO films.