Two-bit-per-cell resistive switching memory device with a Ti/MgZnO/Pt structure

We report the fabrication and characterization of resistive random access memory (RRAM) with a Ti/MgZnO/Pt structure at room temperature. Four different resistive states are obtained by applying different stop voltages (V_stop) for the reset process. These four resistance states show good retention characteristics without any degradation and can be clearly distinguished from one another by more than 10 000 seconds under 100 mV stress. The current transport mechanism is dictated by a Schottky emission as the stop voltage V_stop increases from 1 to 1.5 V. The mechanism of multilevel RS is investigated and band diagrams are used to explain the multilevel RS phenomenon associated with Ti/MgZnO/Pt based RRAM devices.