We observe that γ-ray radiation affects the formation of the conducting bridge in Ag/Ti/Al:HfO2/Pt devices. We suggest that the γ-ray breaks Hf-O bonds and affects the properties of metal/insulator interfaces. The radiation-induced interfacial layers promote the transition from write-once-read-many times (WORM) to reversible switching memories. The devices that undergo a higher radiation exposure exhibit a higher forming voltage that we could exploit to sense radiation; an electrical circuit to harness this phenomenon is also proposed. We also observe that the devices exhibit self-healing behavior, where the forming behavior restores once the radiation energy is released. The switching mechanism is explained and proposed to elucidate this phenomenon. This study not only provides insight into the development of memristor devices for space application but also their potential as multipurpose elements for reconfigurable circuits.

The feasibility of memristor devices as a controllable resistor element for making tunable analogue filters is investigated by employing the Stanford Resistive Random Access Memory (RRAM) memristor model. Replacing the resistor in a conventional filter with a memristor allows the filter to have a variable range, this would solve the limitation where the conventional analogue filters have only a single filter range due to the fixed values of their constituent elements. This paper reports the results of fitting the Al: HfO2 memristor using the Stanford RRAM model, and the fitted results can be perfectly matched to real experimental results. Memristor-based filters can obtain at least two different filter ranges with the same filtering effect as conventional filters.

The implementation of two-terminal memristors could decrease the dependency on the transistors in logic circuits, enabling high-density circuits and reducing power consumption due to the memristor's smaller feature size and non-volatility, respectively. We propose universal logic function designs using ZnO-based transparent memristors. A highly accurate fitting of set and reset curves is achieved by employing Verilog model and used for circuit-level simulations. OR, NOR, NAND, and AND gates can be designed by simply tuning the memristor and pullup resistor while using a similar circuit configuration. Based on this facile configuration, more complex circuits, such as XOR and XNOR gates as well as half-adder and half-subtractor combinational logic circuits can be achieved. This work highlights a promising alternative for reconfigurable logical integrated circuits.

Memristors with various switching characteristics could realise low-power reconfigurable electronics. This paper reports the coexistence of nonvolatile and volatile switching characteristics in Ag/Ti/ZnO/TiN CBRAM memristor devices and examines the feasibility of the cycle-to-cycle fluctuation of both characteristics for memory and random number generator (RNG) applications. A circuit design exploiting the nonuniformity to produce random bits is proposed. We show that random bits can be produced by the circuit regardless of the nonvolatile switching characteristics; nevertheless, volatile behavior may be preferred for low-power operation. Nonvolatile-tovolatile switching transformation can be achieved by inserting an excessively thick barrier layer or applying a low current compliance to form a metastable conducting bridge. We found a close correlation between the statistical distribution of the switching nonuniformity and the randomness parameter for making reliable random bits.

This study aims to exploit the resistance states of Cr/ZnO/TiN memristors to generate random numbers. A random number generator (RNG) circuit employing a single memristor is proposed. We suggest that current compliance (CC) is a significant parameter in determining the quality of randomness; it is found that low CCs (20-50 μA) have a wide resistance state distribution that facilitates random bits. This work provides insight into the implementation of memristors for data security applications.