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.