Fabrication of a W/CuxO/Cu memristor with sub-micron holes for passive sensing of oxygen

Memristive devices were fabricated and investigated for passive sensing of oxygen. The device design involved deposition of Cu bottom electrodes, oxygen-deficient copper oxide (CuxO) switching layers, and W top electrodes in a crossbar array structure. Two groups of holes that were 300 nm and 700 nm in diameter were etched in the top W electrodes to reveal the oxide surface. The devices were subjected to ambient air at 180 degrees C to induce sensing in minutes. Measurements of atomic composition, which were determined via energy-dispersive X-ray spectroscopy (EDS), show an increase in oxygen atoms in the layer after exposure to ambient air. For the 300-nm holes, low and high resistance states demonstrated increased values (up to 25.0% and 74.8%, respectively) upon exposure to ambient air at 180 degrees C. The larger 700-nm holes became capacitor-like after exposure. This work demonstrates a step towards the use of the memristor as a passive gas sensor, which we have named memsensors, by taking advantage of the device's ability to memorize (or record) historical information. (C) 2016 Elsevier B.V. All rights reserved.