Low-Temperature Processed Al-Doped HfO ₂ Ferroelectric Memristor with IGZO Exhibiting High Polarization, Endurance, and Retention

The rapid expansion of Internet of Things (IoT) and artificial intelligence (AI) technologies has intensified the demand for high-density, nonvolatile memory devices offering high reliability and low power consumption. In this study, Al-doped HfO2-based ferroelectric memristors integrated with an indium gallium zinc oxide (IGZO) capping layer were systematically investigated under a constrained thermal budget of 450 °C. Atomic layer deposition (ALD) was employed to precisely control Al doping concentrations ranging from 2 to 8%, achieving uniform dopant distribution through a layered structural design. Optimal ferroelectric and resistive switching behavior was observed at an Al concentration of 3.2%, corresponding to a maximum polarization (Pmax) of 28 μC/cm2. The fabricated devices exhibited characteristic butterfly shaped capacitance–voltage (C–V) curves with distinct negative capacitance (NC) regions, as well as pronounced current–voltage (I–V) hysteresis, indicative of robust resistive switching. X-ray photoelectron spectroscopy (XPS) analysis revealed that the increase in oxygen vacancy concentration, correlated with Al doping levels, significantly influenced the polarization, NC effects, and switching performance. Furthermore, the IGZO capping layer effectively suppressed interfacial charge trapping and eliminated the wake-up effect, thereby enabling stable operation beyond 108 electrical cycles. These findings emphasize the critical role of doping concentration and interface engineering and position Al-doped HfO2 memristors with IGZO integration as promising candidates for scalable, low-power, and high-reliability nonvolatile memory solutions in next-generation display technologies.