Al-Engineered Anatase/Rutile TiO₂ Heterostructures for Superior Resistive Switching

  Resistive switching (RS) devices are promising candidates for next-generation non-volatile memory and neuromorphic computing; however, realizing stable, low-power, and reproducible switching remains a key challenge. Here, we demonstrate ultrafast bipolar RS in TiO₂-based devices by introducing an ultrathin Al-Engineered Anatase/Rutile TiO₂ (Al–A/R-TiO₂) interlayer.

  The Al–A/R-TiO₂/FTO structures exhibit a two-step switching mechanism that synergistically combines interfacial charge trapping with filamentary conduction. Structural and electrical analyses reveal that the engineered interlayer regulates oxygen vacancy dynamics, suppresses filament overgrowth, and stabilizes charge transport. Low-frequency noise (LFN) spectra further confirm robust filament conduction in the low-resistance state (LRS) and defect-assisted transport in the high-resistance state (HRS). Complementary density functional theory (DFT) calculations show that Al incorporation enhances the electronic conductivity of anatase/rutile heterostructures relative to pristine TiO₂, in agreement with the experimental findings.

  As a result, the devices achieve low operating voltage (~1.5 V), a high ON/OFF ratio (>10³), long retention (>10⁵ s), excellent endurance (>10⁴ s), and ultrafast switching (<500 ns) without requiring a forming process.

  This work establishes a robust interfacial-engineering strategy that resolves the long-standing trade-off between stability and performance in oxide-based RRAM and provides a scalable pathway toward energy-efficient, high-speed memory and neuromorphic architectures.