Effect of hydrogen ions in the adsorbed water layer on the resistive switching properties of hexagonal WO3 nanowire

Abstract

The current-voltage characteristics and resistive switching mechanisms, based on the two-terminal Au/hexagonal WO3 nanowires/Au devices, have been investigated under different relative humidity levels. Under high relative humidity, the hydrogen ions produced by hole oxidizing adsorbed water molecules will drift to the negatively biased electrode in the adsorbed water layer based on the Grotthuss mechanism and accumulate near the negatively biased electrode, which will deplete the itinerant electrons and increase the height of the Schottky barrier prominently. The electrical transport properties are dominated by the electrode-limited conduction mechanism (Schottky emission). Once the bias voltage is larger than a critical value, these accumulated hydrogen ions are reduced to hydrogen immediately by the hot electrons injected from the negatively biased electrode, and then the electrical transport properties are dominated by the bulk-limited conduction mechanism (Poole-Frankel emission). It also indicates that the accumulation and reduction of the hydronium ions and then the electrical transport properties can be well regulated by adjusting the initial height of the interfacial barriers. The generation and accumulation of hydrogen ions induced by the bias voltage endows the device based on hexagonal WO3 nanowires with more abundant resistive switching properties.