Aliovalent Ta-Doping-Engineered Oxygen Vacancy Configurations for Ultralow-Voltage Resistive Memory Devices: A DFT-Supported Experimental study

Alteration of transport properties of any material, especially metal oxides, by doping suitable impurities is not straightforward as it may introduce multiple defects like oxygen vacancies (V-o) in the system. It plays a decisive role in controlling the resistive switching (RS) performance of metal oxide-based memory devices. Therefore, a judicious choice of dopants and their atomic concentrations is crucial for achieving an optimum V-o configuration. Here, we show that the rational designing of RS memory devices with cationic dopants (Ta), in particular, Au/Ti(1-x)TaxO(2-delta)/Pt devices, is promising for the upcoming non-volatile memory technology. Indeed, a current window of similar to 10(4) is realized at an ultralow voltage as low as 0.25 V with significant retention (similar to 10(4) s) and endurance (similar to 10(5) cycles) of the device by considering 1.11 at % Ta doping. The obtained device parameters are compared with those in the available literature to establish its excellent performance. Furthermore, using detailed experimental analyses and density functional theory (DFT)-based first-principles calculations, we comprehend that the meticulous presence of Vo configurations and the columnar-like dendritic structures is crucial for achieving ultralow-voltage bipolar RS characteristics. In fact, the dopant-mediated Vo interactions are found to be responsible for the enhancement in local current conduction, as evidenced from the DFT-simulated electron localization function plots, and these, in turn, augment the device performance. Overall, the present study on cationicdopant-controlled defect engineering could pave a neoteric direction for future energy-efficient oxide memristors.

Automated summary

By doping appropriate cationic dopants, metal oxide-based RS devices can achieve excellent performance with low current, long retention time, and endurance at ultralow voltage. The presence of Vo configurations and columnar-like dendritic structures is crucial for achieving these characteristics.