Non-Volatile Resistive Memory Switching in Pulsed Laser Deposited Rare-Earth Gallate-GdGaO3 Thin Films

Resistive random access memories (ReRAMs) have emerged as a potential memory candidate that has the capability of fulfilling the future high density requirements due to their simple design, excellent scalability, high speed storage capacity, low power consumption, and CMOS process-flow compatibility. With this motivation pulsed laser-deposited amorphous GdGaO₃ (GGO) thin films sandwiched between two Pt-electrodes were investigated to explore their resistive switching (RS) behaviour. Pt/GGO/Pt memory cells showed a stable resistance ratio of ~10⁴ between low resistance state (LRS) and high resistance state (HRS) and non-overlapping switching voltages (set voltage V_ON ~1.2˗1.4 V and reset voltage V_OFF ~0.5˗0.7 V) with a small variation of 5˗10%. To confirm the reliability of the Pt/GGO/Pt memory cells, cyclic endurance up to 60 set/reset cycles and data retention up to 10³ seconds were measured. Only a unipolar RS mechanism in Pt/GGO/Pt memory cells was observed due to a conductive filamentary (thermo-chemical) mechanism in which, the change in resistance state (LRS↔HRS) of the cell was found to occur from rupture of conductive filaments consisting of metallic Gd atoms and oxygen vacancies. The charge transport mechanisms of the cell in LRS and HRS states were found to be dominated by Ohmic conduction and trap controlled space–charge limited current, respectively. This work reveals the potential of rare-earth gallates for non-volatile memory device applications.