<p>The rapid advancement of artificial intelligence has increased the demand for high-performance memory, thereby emphasizing the need for next-generation non-volatile memory solutions such as resistive random-access memory (RRAM). In this study, Y₂O₃-based RRAM devices were fabricated on ITO-coated glass substrates using the sol–gel method. The concentration of oxygen vacancies in the Y₂O₃ films was controlled by incorporating HNO₃, a well-known strong oxidizing agent. The structural, chemical, and electrical properties of the films were analyzed as a function of HNO₃ concentration. As the HNO₃ amount increased, the resulting films became thinner and more uniform, exhibiting minimal cracks or pinholes, thereby achieving high-quality Y₂O₃ layers. Additionally, the oxidizing nature of HNO₃ reduced the concentration of oxygen vacancies in the Y₂O₃ films. RRAM devices based on HNO₃-treated Y₂O₃ demonstrated lower SET voltages, attributed to the reduced film thickness and enhanced high-resistance state (HRS) resulting from fewer oxygen vacancies, which otherwise serve as leakage current pathways. The lower vacancy concentration also suppressed random and excessive conductive filament growth between the electrodes. This led to increased HRS values and improved endurance and retention characteristics of the non-volatile RRAM devices. The Y₂O₃ RRAM devices fabricated with HNO₃-modified precursors exhibited a high HRS/LRS ratio, exceeding ~ 10⁶, endurance up to 10³ cycles, and data retention beyond 10⁴ s without notable degradation. This study provides valuable insights into optimizing the sol–gel deposition of Y₂O₃ via HNO₃ modulation for RRAM architectures, representing a significant step toward developing reliable and stable non-volatile memory technologies.</p>