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/Ti1-xTaxO2-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 V-o configurations and the columnar-like dendritic structures is crucial for achieving ultralow-voltage bipolar RS characteristics. In fact, the dopant-mediated V-o 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 cationic-dopant-controlled defect engineering could pave a neoteric direction for future energy-efficient oxide memristors.

Automated summary

This study investigates the effect of cationic dopants on metal oxide-based memory devices and demonstrates that rational designing of RS memory devices with cationic dopants can lead to excellent resistive switching performance. Experimental analyses and calculations reveal the crucial role of V-o configurations and columnar-like dendritic structures in achieving ultralow-voltage bipolar RS characteristics.