Redox-Active Vanadium-Based Polyoxometalate as an Active Element in Resistive Switching Based Nonvolatile Molecular Memory

Abstract

Resistive switching (RS)-based random access memory has been envisaged as a viable alternative to existing memory technology due to its nonvolatility, high switching speed, high endurance/retention, and considerably low operating voltage. Herein, a new uniform, repetitive, and stable RS phenomenon is demonstrated based on very low-cost two-terminal metal–insulator–metal stack fabricated using a highly redox-active vanadium-based polyoxometalate (POM) molecular clusters, [V<inf>10</inf>O<inf>28</inf>]6?—belonging to polyoxovanadate (POV) family. The RS is observed to be unipolar and nonvolatile in nature, and occur at a fairly low operating bias voltage (less than 2 V), making it suitable for low-power operations. The switching event is attributed to the cycling between formation and rupture of tiny conductive nanofilaments formed due to trapping and detrapping of positively charged ionized oxygen vacancy sites present in the active switching layer of [V<inf>10</inf>O<inf>28</inf>]6?. POMs, in their rich abundance, are highly stable early transition-metal oxide nanosized clusters, capable of storing as well as releasing a large number of electrons. In addition, they can undergo fast and reversible redox reactions (both in solid and liquid electrolyte media) in “stepwise” manner—a property that makes them a promising candidate for ultrafast and multi-level nonvolatile molecular memory for high-density data storage. Preliminary investigations on the POV-based memory cells result in device resistance ratio ?25, endurance for more than 200 cycles, and stable retention time around 2200 s, in fully open air condition. © 2020 Wiley-VCH GmbH