Coexistence of bipolar and threshold resistive switching in TiO2 based structure with embedded hafnium nanoparticles

The coexistence of nonvolatile memory switching and volatile threshold switching in a single device is of importance for suppressing the sneak-path currents in crossbar resistive memory architectures. This study demonstrates that the combination of a thin film of TiO2 with hafnium nanoparticles in Au/Ti/TiO2/Hf nanoparticles/Au device configuration enables conversion between memory switching and volatile threshold switching by adjusting the current compliance through the materials stack. The presence of hexagonal closed packed Hf nanoparticles, a synthesis of which has not been reported before, is critical for the device operation that exhibits beneficial features as it is forming free and operates at low voltage and power consumption. Analysis of measured current-voltage (I-V) characteristics reveal a filamentary nature of switching phenomena and present operating similarities with electrochemical metallization cells suggesting that Hf metal atoms and not only oxygen vacancies are responsible for conductive filament formation.