Electro-ferroelectric characterization of nicotinium tetrachloridocuprate(ii) memristor for prospective neuromorphic applications

Abstract

Nicotinium tetrachloridocuprate(II) (NICu) with the triclinic system and P1 space group was synthesized and the device made of thin layer sandwiched between ITO and Cu electrode (ITO/NICu/Cu) was investigated. The corresponding current–voltage curves of the devices display ohmic conduction at low applied voltages (±0.5 V) to pinched hysteresis loops at higher voltages (±1 V and ±2 V). Pulse-based measurements revealed an ON/OFF ratio of 2. The ON state (low resistance) gradually decayed back to the OFF state (high resistance) over approximately 8 hours during the retention experiment. Further assessment in endurance tests confirmed reliable switching performance over more than 1000 cycles. The synaptic behavior of the fabricated device was investigated by applying symmetric pulses with amplitudes ranging from ±0.6 V to ±2.2 V and a duration width of 0.005 s and 0.01 s. Longer pulse widths increased conductance during potentiation but reduced the effectiveness of depression step. In contrast, pulses with short width result in more reversible and balanced conductance modulation with better control over synaptic weight changes. Apart from studying the solid-state properties, the diffusive-memristive behavior of NICu in dimethylformamide solution in a two-electrode setup was investigated, revealing highly promising characteristics for the development of liquid-state information processing systems. Additionally, the study of large amplitude sinusoidal voltammetry confirms the memfractance characteristic of solid-state devices in low-temperature and low-frequency studies. The ON/OFF ratio, retention, endurance, and synaptic characteristics collectively demonstrate the potential of NICu memristor as an artificial synapse for prospective neuromorphic computing applications.