Coexistence of Electrode-Dependent Resistive Switching and Negative Differential Resistance Effect in α-MoO3-x Memristor

Abstract

This work presents the filamentary resistive switching (RS) of transition metal oxide thin film planner memristors, specifically focusing on α-MoO₃, a distinguished n-type wide bandgap semiconductor. The study uncovers the metal electrode-dependent negative differential resistance (NDR) effect and memristive behavior of α-MoO₃ thin films for next-generation non-volatile memory and neuromorphic computing applications. The silver (Ag) electrode exhibits superior bipolar RS than the titanium (Ti) electrode because of Ag ion diffusions, the nature of the Ag/MoO₃ junction, and interfacial effects. Likewise, significant NDR is observed for the Ag electrode compared to the Ti, owing to thermally activated transport, residual ionic motion, and redox processes at the Ag electrode. Transient measurements reveal stronger spike-like current responses for the Ag electrode, emphasizing its potential for neuromorphic devices. Besides, the optical absorption and photoluminescence analysis show that oxygen vacancies create Mo⁺⁵ defect states and split the Mo d-level owing to the crystal field effect, which affects the electronic structure and visible light emission of α-MoO₃ thin film. These findings demonstrate the essential role of metal electrodes and defect engineering in controlling filamentary RS and NDR effect, advancing α-MoO₃ thin films for future neuromorphic computing and optoelectronic devices.