Resistance change in memory structures integrating CuTCNQ nanowires grown on dedicated HfO2 switching layer

The present paper deals with the bipolar resistive switching of memory elements based on metal-organic complex CuTCNQ (copper-7,7’,8,8’-tetracyanoquinodimethane) nanowires grown on a dedicated HfO₂ oxide switching layer. Switching characteristics are explored either at millimeter scale on pad-size devices or at nanoscale by using conductive atomic force microscopy. Whatever the investigation scales, the basic memory characteristics appear to be controlled by copper ionic transport within a switching layer. This latter corresponds to either HfO₂ layer in pad-size devices or nanogap formed at nanoscale between the atomic force microscopy conductive tip and CuTCNQ surface. Depending upon the observation scale, the switching layer (either HfO₂ oxide or nanogap) acts as a matrix in which copper conductive bridges are formed and dissolved thanks to redox processes controlled in alternating applied bias voltages.