Tuning TiO₂ Memristors by Defect Engineering: From Short-Term Memory to Recoverable Long-Term Resistance States

Resistive switching memory cells (memristors), with potential applications in neuromorphic computing and next-generation data storage, were studied. Sputter-deposited samples of Pd/TiO₂/Pd memristor structures exhibited bipolar switching with long-term (nonvolatile) memory after an initial electroforming process. The samples were subsequently implanted with 8 keV ¹⁶O and ²⁰Ne ions to tune switching properties by controlled introduction of defects in the TiO₂ layer. A modification in the oxygen vacancy concentration resulting from the implantation was verified using X-ray photoelectron spectroscopy with both Al and Ga Kα X-rays. Ion implantation enabled electroforming-free RS with short-term (volatile) memory and weighted resistance states with long-term memory, which can be modulated via compliance current, in addition to the RS with long-term memory exhibited by the as-prepared samples. The potential underlying mechanism for switching in ion-implanted memristors is discussed, relating it to the tuning of switching properties through ion implantation. Ion-implanted samples, which exhibited electroforming-free short-term memory, showed a decrease in failure rate. These findings highlight the potential of ion implantation as a versatile tool for tuning switching characteristics of memristors.