Reset First Resistive Switching in Ni(1−x)O 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 Ni(1−x)O thin films deposited using reactive sputtering with a high oxygen partial pressure. The Ni(1−x)O based RRAM devices exhibited both unipolar and bipolar resistive switching characteristics without an electroforming step. Auger electron spectroscopy showed nickel deficiency in the Ni(1−x)O films, and X-ray photoemission spectroscopy showed that the Ni(3+) valence state in the Ni(1−x)O films increased with increasing oxygen partial pressure. Conductive atomic force microscopy showed that the conductivity of the Ni(1−x)O films increased with increasing oxygen partial pressure during deposition, possibly contributing to the reset-first switching of the Ni(1−x)O films.