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Keywords:

  • bilayer;
  • lightning-rod effect;
  • resistance switching;
  • uniformity

Abstract

Memory performances, especially uniformity and reliability of resistance random access memory (RRAM) devices with W/NbOx/Pt structures were investigated. Scaling down the active device area (ø = 250 nm) can significantly minimize extrinsic defects related to nonuniform switching and also demonstrate low-voltage SET/RESET operations due to increased Joule heating. Electromigration of oxygen ions under the bipolar electric field, bilayer formation, and lightning-rod effect localized at WOx/NbOx interface can explain the improved switching behavior in this novel stack. Excellent device characteristics such as lower switching voltage, fast switching speed (100 ns), high-temperature retention (>104 s, 85 °C), stable cycling endurance (107 cycles), almost 100% device yield and excellent switching uniformity are obtained.