Fabrication of bilayer ITO/YZO/PMMA/Al memory devices with insight ternary switching mechanism

Abstract

Two terminal resistive switching memories are emerging candidates for the next generation of non-volatile memory in the upcoming era of artificial intelligence and big data generated globally. Much research is currently focused on developing write-once-read-many-times (WORM) memory devices, which offer the advantages of small size, high speed, improved energy consumption, and large data capacity. Nanostructured organic/inorganic heterojunction composites have garnered significant attention due to their excellent scalability and low-cost fabrication. In the present study, the YZO/PMMA hybrid nanocomposite bilayer ReRAM was fabricated on ITO substrates. The I-V characteristics of the fabricated ITO/YZO/PMMA/Al device exhibited the ternary WORM switching behavior (HRS, LRS1, and LRS2 states). It has been observed that three states of “HRS”, “LRS1” and “LRS2” exhibit a distinct current ratio of LRS1/HRS and LRS2/HRS of 10^1.6 and 10^2.4_, respectively, with good data retention (up to 500 h). It was demonstrated that Y-dopant concentration into ZnO significantly transits the switching behavior of ITO/ZnO/PMMA/Al memory from binary to ternary WORM switching characteristics. Ohmic conduction and space charge-limited current (SCLC) were observed in the HRS. In LRS1, the Schottky emission mechanism was observed, while in LRS2, Ohmic conduction was observed. The physical model of the formation of permanent conducting filaments (CFs) consisting of oxygen vacancies in the device's active layer is proposed to explain the RS behavior. These findings reveal the low-cost development of high-density, non-volatile memory devices operated with very low power consumption that can be used to protect data against unauthorized software/hardware and hackers.