Ferroelectric, phase-change, and magnetic materials are considered promising candidates for advanced memory devices. Under the development dilemma of traditional silicon-based memory devices, ferroelectric materials stand out due to their unique polarization properties and diverse manufacturing techniques. On the occasion of the 100th anniversary of the birth of ferroelectricity, scandium-doped aluminum nitride, which is a different wurtzite structure, was reported to be ferroelectric with a larger coercive, remanent polarization, curie temperature, and a more stable ferroelectric phase. The inherent advantages have attracted widespread attention, promising better performance when used as data storage materials and better meeting the needs of the development of the information age. In this paper, we start from the characteristics and development history of ferroelectric materials, mainly focusing on the characteristics, preparation, and applications in memory devices of ferroelectric wurtzite AlScN. It compares and analyzes the unique advantages of AlScN-based memory devices, aiming to lay a theoretical foundation for the development of advanced memory devices in the future.

The combination of high-performance materials and simplified multilayer fabrication processes can promote the rapid and high-quality development of memristors. In this work, we proposed wide-bandgap semiconductor silicon carbide (SiC)-based memristors fabricated entirely by electron beam evaporation technology. The Cu/SiC/Pt structure was fabricated on a 2-inch intrinsic silicon substrate, which can achieve a transition from volatility to non-volatility. Devices had a low and symmetric switching voltage of ±0.5 V, an endurance of >200 cycles, a retention of >103 s, an ON/OFF ratio of ∼103, and can achieve at least 6 different stable resistance states. The combined effects of traps and Cu conductive filaments caused the current to change abruptly during switching, while also possessing excellent synaptic plasticity and pulse programming ability. Our work demonstrated that wide-bandgap semiconductor SiC is a promising candidate for advanced memristors.

Employing suitable materials and device engineering is one of the crucial methods toward the realization of multifunctional memristive devices for constructing bioinspired neuromorphic systems. In this work, dual-functional memristors composed of eco-friendly natural silk sericin, coexistently enabling the achievement of threshold switching and memory switching triggered by adjusting the compliance current value, have been fabricated with a specific two-terminal device structure: Ag/Ag−In−Zn−S/silk sericin/W. Experimentally, the as-manufactured memristors exhibit several desirable qualities, such as low switching voltage (< 0.7 V), relatively small cycle-to-cycle and device-to-device variabilities, nonvolatile multilevel storage characteristics, and rapid switching speed (40 ns). Beyond these qualities, fundamental synaptic behaviors, such as paired-pulse facilitation and spike-timing-dependent plasticity (STDP), have been mimicked. This was made possible by a filamentary mechanism based on Ag migration. The fitted time constants corresponding to the STDP potentiation and depression are about 30 ms, and the highest changes in synaptic weight for positive and negative voltage pulses are 84.4% and 61.7%, respectively. Furthermore, the typical coincidence detection task has been executed, demonstrated by simulation based on the fitted STDP's parameters of the sericin-based device. The results from this study indicate that the sericin-based memristors, as designed, have the potential to be employed in the creation of versatile neuromorphic devices for neuromorphic computing systems.

Ultra-wide-bandgap semiconductor aluminum nitride (AlN) has demonstrated many excellent characteristics and is a promising candidate for advanced memristor dielectrics. Numerous stacked structures have been attempted in recent years, but research on simpler symmetrical electrodes structure and unipolarity is still insufficient. Here, we designed symmetrical Al electrodes structure with unipolarity that can realize Forming, Set, and Reset processes through voltage in only one direction. With good consistency, we can achieve ROFF/RON ratio of >105, resistance states of >8, retention time of >104 s, and pulse programmable characteristics. Through the research on temperature and size, we have revealed the asymmetric conduction mechanism under the symmetrical structure. At the same time, we also achieved the integration of erasable and non-erasable arrays on a single chip. Compatibility with CMOS technology indicates that our devices will be very promising for integration with other modules, providing inspiration for enriching the application of AlN-based memristors.

Metal oxides are the most widely used material for the resistive switching layer of memristors. Nevertheless, the majority of oxide-based memristors exhibit binary switching, restricting the emulation of neuronal synaptic behaviors. In this paper, the shift from digital-to-analog switching behavior is achieved by inserting an Al₂O₃ layer atop Zr-doped HfO₂. The TiN/Al₂O₃/HZO/W/Si device exhibits long resistance state retention time and consistency. In addition, by applying a varying voltage, the device exhibits up to 20 continuous resistance states, which is highly significant for high-density storage. Upon the application of a programmable pulse signal, the device’s conductance undergoes continual alteration, reflecting long-term potentiation (LTP) and long-term depression (LTD) synaptic characteristics. The conduction mechanism of the device is studied through physical model fitting and schematic diagrams.

The Ga₂O₃-based memristors, fabricated via electron beam evaporation (EBE), exhibit both volatile and nonvolatile resistive switching behaviors. The nonvolatile Ga₂O₃-based memristors exhibit remarkable resistive switching properties, featuring outstanding cyclic stability, a substantial switching window (>100), and notably low SET/RESET voltages. The observed dual switching modes are attributed to filamentary conduction driven by metallic Cu filaments assisted by oxygen vacancies. The studied Ga₂O₃-based devices demonstrate both electrically and optically tunable synaptic functionalities, including paired-pulse facilitation (PPF), spike-rate-dependent plasticity (SRDP), spike-timing-dependent plasticity (STDP), potentiation and depression behaviors, as well as light-induced memory characteristics and learning-forgetting capabilities. Intriguingly, high recognition precision of 89.14% on Fashion-MNIST and 97.84% on modified National Institute of Standards and Technology database (MNIST) indicates that wide bandgap semiconductor Ga₂O₃-based memristors hold immense potential for advancing future neuromorphic computing.