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

Abstract

The physical mechanisms of unipolar resistive switching (RS) in SiOx-based resistive memory are investigated using TaN/SiOx/n++Si and TiW/SiOx/TiW device structures. RS is independent of SiOx 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 SiOxNy 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 SiOxNy 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 SiOx defects. High-temperature data retention measurements for over 104 s in high- and low-resistance states demonstrate the potential for use of intrinsic SiOx RS devices in future nonvolatile memory applications.