Defect-Engineered Resistive Switching in van der Waal Metals

In this work, we demonstrated bipolar resistive switching (RS) in van der Waals metals [tantalum di-sulfide (2H-TaS2), tantalum di-selenide (2H-TaSe2)], and their heterostructures (2H-TaS2/2H-TaSe2) by engineering defects through joule heating mechanism. Localized heating is achieved by injecting current to the van der Waals metals and the induced defects were found to be mostly chalcogenide vacancies. The vacancies act as dynamic charge-trapping and de-trapping sites within the material structure, thereby inducing RS in the device. The SET/RESET process is controlled by changing the direction of the current flow, a behavior that is very similar to that of a memristor. But unlike a memristor, the reported device has a completely different architecture with no oxide or semiconducting active layer. Temperature-dependent studies revealed that the carrier transport is dominated by space-charge limited conduction and sharp switching occurs due to the voltage-driven modulation of potential barrier heights at the region containing the defects. The study offers a simple alternative to conventional two-terminal resistive switches and the potential of van der Waals metals for the advancement of memristive devices.