Introduction: Resistive random access memory devices are crucial in nonvolatile memory applications. Hafnia- and zirconia-based devices are extensively researched due to their diverse properties. However, more insights are needed to enhance the performance of HfO₂-based resistive switching devices.

Method: Thin films of Zr_xHf_1–xO₂ were deposited using co-sputtering on n-type Si (100) substrates at room temperature. The films were deposited at different powers i.e. at 1,3,5 and 7 W onto the Zr target while keeping the RF power to the Hf target at 50 W. Various techniques including X-ray photoelectron spectroscopy, differential scanning calorimetry, and thermogravimetric analysis were employed for physical characterization. Additionally, electron beam evaporation was used for top metal deposition and patterned using UV photolithography to get 100µm diameter gate electrodes.

Results: XPS analysis revealed complete oxidation of Zr metal during sputtering and all the film contain non-lattice oxygen. The Zr concentration in the as-deposited films ranged from 8% to 11%. Devices with 9% Zr concentration exhibited the best resistive switching performance. DSC studies indicated an endothermic peak at 145.9°C for films doped with 9% Zr, confirming lattice oxygen release. Presence of non-lattice oxygen is not the sole criterion for achieving a better resistive switching property, release of lattice oxygen is also necessary. The liberated lattice oxygen can be reversibly restored to their original sites at elevated temperatures, thereby reinstating the high-resistance state. Increasing doping concentration improved current fluctuations at low- and high-resistance states.

Conclusions: This study underscores the significance of non-lattice and lattice oxygen as well as Zr concentration in achieving desirable resistive switching properties in Zr_xHf_1–xO₂ thin films. These findings hold implications for enhancing non-volatile memory device performance.