Nonvolatile Multilevel Conductance and Memory Effect in Molecule-Based Devices

Electrical characteristics of a single-layer organic device using 2-(hexahydropyrimidin-2-ylidene)-malononitrile (HPYM) that is interposed between Al/Al₂O₃ (cathode) and Ag (anode) electrodes were investigated. The application of different positive voltages produced different high-conductance currents, resulting in the multilevel memory capability of the device. The high-conductance states could be erased back to the low-conductance state by the application of a negative bias. The formation of an aluminum oxide layer between Al and HPYM layer could be one effective method to increase the data-retention time but could be irrelevant with the electric-field-induced conductance-state transition of the device.