Intrinsic SiO_x-based unipolar resistive switching memory. I. Oxide stoichiometry effects on reversible switching and program window optimization

The physical mechanisms of unipolar resistive switching (RS) in SiO _x-based resistive memory are investigated using TaN/SiO _x/n⁺⁺Si and TiW/SiO_x/TiW device structures. RS is independent of SiO_x thickness and device area, confirming that RS occurs in a localized region along a filamentary pathway. Results from experiments varying electrode type, series resistance, and the oxygen content of SiO_xN_y materials show the potential to optimize switching performance and control device programming window. Device materials with stoichiometry near that of SiO₂ are found to have better operating stability as compared to extrinsic, N-doped SiO_xN_y materials. The results provide further insight into the physical mechanisms of unipolar operation and lead to a localized switching model based on electrochemical transitions involving common SiO_x defects. High-temperature data retention measurements for over 10⁴ s in high- and low-resistance states demonstrate the potential for use of intrinsic SiO_x RS devices in future nonvolatile memory applications.