Study of conduction and switching mechanisms in Al/AlOx/WOx/W resistive switching memory for multilevel applications

In this letter, the conduction and switching mechanisms of Al/AlOx/WOx/W bilayer resistive random access memory devices are investigated. Five stable resistance states were achieved through current compliance control. For each resistance state, I-V characteristics at different temperatures were measured. Conduction mechanisms are found to vary with resistance states. At low resistance levels, devices show ohmic conduction with metallic behavior. Conduction at medium resistance levels is due to electron hopping. The carrier transport at high resistance levels is governed by Schottky emission. Based on the resistance-dependent transport characteristics, an oxygen migration model is proposed to explain the switching mechanism between different resistance states.