High resistive switching on/off ratio in Lu doped Hf0.4Zr0.6O2 thin films through band structure and vacancy co-strategy

Abstract

Fluorite-structured oxides (HfO₂, ZrO₂) are ideal materials for resistive random-access memory (RRAM) due to their scalability and adjustable structural and electrical characteristics. The high-resistive switching windows are essential for improving reading accuracy in memory applications. Here, we adopted a collaborative strategy by optimizing the Hf/Zr ratio and Lu³⁺ doping to regulate the band structure and oxygen vacancy concentration, which significantly influence intrinsic leakage currents and the formation of conductive filaments. The resulting Lu-doped Hf_0.4Zr_0.6O₂ (LHZO) thin films achieve a resistive switching ratio of 8.4 × 10⁴, which is two orders of magnitude higher than that of ZrO₂ thin films (1.2 × 10³). Electrical characterization and synchrotron radiation photoemission spectroscopy confirm that enhanced insulating properties and increased oxygen vacancies are pivotal for suppressing off-state conduction and stabilizing conductive filaments in the on-state. These findings show that the co-optimization of band structure and oxygen vacancy effectively regulates the electrical characteristics of fluorite-structured oxides as high-performance RRAM.