Electroforming Free Non-Volatile Resistive Memory Switching in Pulsed Laser Deposited Rare-Earth Oxides Thin Films

In resistive random access memory (ReRAM) device, an electroforming process is necessary to activate the resistive memory cell and requires an extra high-voltage source in the memory circuit which leads to high power consumption and complex circuit design. Therefore, electroforming free reproducible resistive switching (RS) phenomenon in ReRAM is required to reduce the power consumption, to simplify the circuit design and to have better uniformity in the device performance. Herein, we present the non-volatile RS behaviour of pulsed laser deposited polycrystalline thin films of rare-earth oxides. The electroforming free stable unipolar RS behaviour was observed in Pt/RE₂O₃/Pt memory cells (RE = Sm and Gd). The Pt/RE₂O₃/Pt cells showed a high-resistance ratio in the range of ∼10⁵-10⁶, a good data retention as long as 10⁴ s measured at 100 °C, a reliable endurance for up to 100 cycles, and non-overlapping switching voltages (SET voltage V_ON ~2.7˗3.2 V and reset voltage V_OFF ~ 0.6˗0.9 V). RS mechanism in Pt/RE₂O₃/Pt memory cells can be explained on the basis of oxygen vacancies assisted conductive nano-filamentary (thermo-chemical) model. The dominant charge transport mechanism in the oxide films was ascribed to space-charge-limited-current (SCLC) conduction.