Effects of Vanadium Doping on Resistive Switching Characteristics and Mechanisms of SrZrO₃-Based Memory Films

The effects of vanadium doping on resistive switching (RS) characteristics and mechanisms of RF-sputtered SrZrO3(SZO)-based thin films are investigated in this paper. The physical and electrical properties of SZO-based thin films are modulated by vanadium doping due to the Zr4+ion replaced by V5+, further affecting the RS parameters of SZO-based thin films. The conduction mechanisms of SZO-based thin films are dominated by ohmic conduction (hoping conduction) and Frenkel-Poole emission for the low resistance state (LRS) and the high resistance state (HRS), respectively. The turn-on process might be attributed to the formation of conducting filaments consisting of oxygen vacancies with the effective barrier height (φB,eff) in the range of 0.10-0.13 eV, whereas the turn-off process might result from thermally assisted oxidation of oxygen vacancies by the Joule heating effect. Furthermore, the introduction of the high valence cation (V5+) in a Zr4+site of SZO crystalline structure can suppress the formation of oxygen vacancies due to the charge neutrality restriction. Such suppression leads to the changes in the forming voltage, turn-on voltage, HRS resistance, dielectric constant, and φB,effwith vanadium doping concentration up to 0.2 mol%, which is within the solid solubility limit based on our measured lattice constants and Vegard's law.