Resistive Switching Characteristics of Sol-Gel Derived Zinc-Doped Nd2Zr2O7 Thin Films for RRAM Applications

This study investigates the resistive switching (RS) characteristics of Nd_2(1-x)Zn_2xZr₂O₇ (x = 0, 0.01, 0.03, 0.05, 0.07, 0.09) thin films synthesized via the sol-gel method under varying doping concentrations and thermal treatments. All devices exhibited bipolar switching behavior without requiring a forming voltage. Compared to undoped NZO thin-film devices, the sample with a 5 mol% Zn doping concentration demonstrated superior performance due to the introduction of Zn²⁺ ions, which generate additional oxygen vacancies that dominate the conduction mechanism. After post-metal annealing, it achieved up to 2374 switching cycles, exhibited relatively low operating voltages (1.72 V/0.96 V), and maintained a sufficient Ron/Roff ratio (~10²). This achievement is attributed to the extra oxygen vacancies generated through the thermal treatment. Additionally, the In ions formed during post-metal annealing assist in the formation of conductive filaments. Furthermore, the AlO_x layer functions as an effective oxygen storage layer, preventing oxygen loss to the atmosphere while regulating the release and replenishment of oxygen ions under an electric field. In conclusion, this study presents Nd_2(1-x)Zn_2xZr₂O₇ as a promising RRAM material with significant potential for future applications.