Nanorobotic in situ characterization of nanowire memristors and “memsensing”

We report the nanorobotic in situ forming and characterization of memristors based on individual copper oxide nanowires (CuO NWs) and their potential applications as nanosensors with memory (memristic sensors or “memsensors”). A series of in situ techniques for the experimental investigations of memristors are developed including nanorobotic manipulation, electro-beam-based forming, and electron energy loss spectroscopy (EELS) enabled correlation of transport properties and carrier distribution. All experimental investigations are performed inside a transmission electron microscope (TEM). The initial CuO NW memristors are formed by localized electron-beam irradiation to generate oxygen vacancies as dopants. Current-voltage properties show distinctive hysteresis characteristics of memristors. The mechanism of such memristic behaviors is explained with an oxygen vacancy migration model. The presence and migration of the oxygen vacancies is identified with EELS. Investigations also reveal that the memristic behavior can be influenced by the deformation of the nanowire, showing that the nanowire memristor can serve as a deformation/force memorable sensor. The CuO NW-based memristors will enrich the binary transition oxide family but hold a simpler and more compact design than the conventional thin-film version. With these advantages, the CuO NW-based memristors will not only facilitate their applications in nanoelectronics but play a unique role in micro-/nano-electromechanical systems (MEMS/NEMS) as well.