Reproducible unipolar resistive switching behaviors in the metal-deficient CoOx thin film

Pt/CoOx/Pt tri-layers exhibited reproducible and stable unipolar switching under a dc sweeping voltage. In order to investigate the role of oxygen reduction in the metal-deficient CoOx layer, resistive switching of the post-annealed CoOx thin film was compared with those of the as-deposited CoOx thin film. X-ray photoemission spectroscopy showed larger reproducible resistance switching and decreasing of current level in the post-annealed CoOx thin film. This may be explained by a reduction in oxygen stoichiometry without phase transformation of the CoOx. In addition, stable switching in post-annealed CoOx layer is considered to originate from the decrease of the Co vacancies in local Co3O4 region partially distributed in the whole CoOx layer, not in the dominant CoO.