Two-Step Reset in the Resistance Switching of the Al/TiOx/Cu Structure

Two-step reset behaviors in the resistance switching properties of the top Al/TiOx/bottom Cu structure were studied. During the electroforming and set steps, two types of conducting filaments composed of Cu and oxygen vacancies (Cu-CF and VO-CF) were simultaneously (or sequentially) formed when Al was negatively biased. In the subsequent reset step with the opposite bias polarity, the Cu-CFs ruptured first at ∼0.5 V, and formed an intermediate state. The trap-filled VO-CFs were transformed into a trap-empty state, resulting in a high-resistance state at ∼1 V. Matrix phase in the electrochemical metallization cell can play an active role in resistance switching.