Exploring Electron Transport and Memristive Switching in Nanoscale Au/WO_x/W Multijunctions Based on Anodically Oxidized Al/W Metal Layers

An array of semiconducting tungsten‐oxide (WO_x) nanorods, 100 nm wide and 700 nm long, is synthesized via the porous‐anodic‐alumina‐assisted anodization of tungsten on a substrate and is modified by annealing in air and vacuum. The rods buried in the alumina nanopores are self‐anchored to the tungsten layer while their tops are interconnected via gold electrodeposited inside and over the pores. Thus formed metal/semiconductor/metal microdevices are used for studying electron transport within the nanorods and across the multiplied nanoscale Au/WO_x and W/WO_x interfaces. The dominating effect of a Schottky junction that forms at the Au/WO_x interface is justified for the as‐anodized and air‐annealed nanorods tested at room temperature, which transforms into an ohmic contact at elevated temperature, whereas the bottom W/WO_x interface turns out to be Schottky‐like and govern the electron transport, giving a higher barrier and a set of pronounced diode‐like characteristics in the as‐anodized nanoarrays. The amorphous nanorods reveal bipolar resistive switching with a gradual reset due to the field‐driven movement of oxygen vacancies and induced modifications of the Au/WO_x Schottky interface. The unique electrical and interfacial properties of the nanoscale Au/WO_x/W multijunctions form a basis for their application in emerging resistive random access memories or 3D gas‐sensing nanodevices.